Mahomes, the reigning MVP of the defending Super Bowl champs, has the top-seeded Kansas City Chiefs positioned to repeat. Mayfield just quarterbacked the Cleveland Browns to their first playoff victory in 26 years.
But before the two gunslingers became the faces of their NFL franchises, Mayfield and Mahomes staged one of the wildest shootouts in college football history as Big 12 rivals.
To those who were there in Lubbock that October night in 2016 to watch Oklahoma outscore Texas Tech 66-59, the record-breaking numbers remain almost unfathomable to contemplate.
The two teams combined for an FBS-record 1,708 yards of offense, while Mahomes and Mayfield combined for 1,279 passing yards, also most ever in a college football game.
Mahomes himself set FBS records with 819 yards of total offense and 734 passing yards, while attempting 88 passing attempts -- despite playing through a separated throwing shoulder and fractured left wrist. Mayfield countered with an OU-record seven touchdowns.
"We had to score every single drive in the second half to win that game," Mayfield said this week. "It was an unbelievable game and unbelievable atmosphere. Just the back and forth is something that I will not forget."
To this day, Mayfield and Mahomes remain friendly. In fact, not long before transferring from Texas Tech to OU, Mayfield actually hosted Mahomes during his official visit to Lubbock.
"It's cool to get to play against him in such a big game, in the playoffs," Mahomes said this week. "Known him for a long time, since I was a senior in high school and to be able to play on this stage is going to be special."
As the two quarterbacks prepare for Sunday's showdown, ESPN recounted their remarkable shootout from four years ago through the people there to witness it:
* An earlier version of this story ran Nov. 1, 2018
Mayfield's return to Lubbock
Lincoln Riley: Our kids were really fired up for the game, not just Baker. It was a fun atmosphere, a hostile crowd. All the history of Baker, all the history with our staff, I mean our players talked about that through the week. So we were motivated.
Jessica Coody, Sooner Sports TV: Walking to the stadium, all the fraternity houses had these signs, all these negative comments toward Baker. I was thinking, do you people understand when you make him mad, he plays better? Then when you get in there, it's all these "Traitor" T-shirts.
Seen a few of these shirts in the Texas Tech student section: pic.twitter.com/K0g5eCBHsx— Jake Trotter (@Jake_Trotter) October 22, 2016
Chris Plank, OU radio sideline reporter: I'll never forget the pregame energy. You had a group of fans who just so badly wanted to give it to somebody. They were ready to let him have it.
Chris Level, Tech sideline reporter: He was public enemy No. 1. Baker had played up to that, embraced the heel role. There were signs everywhere. As much as you were going to go cheer for Tech, you were going to cheer against Mayfield. The students were chanting, "F--- you, Baker."
Mayfield: That was my "Welcome back to Lubbock" moment.
Toby Rowland, OU play-by-play voice: There was a lot of venom. There was a lot of excitement on Baker's part. He knew how he was going to be greeted and he loved walking into the lion's den.
Stoops: The only talk I ever had with Baker leading up to the game was just don't try and make this personal or don't make too much of this. You're too good of a player.
Riley: He wants the crowd to chant at him. He feeds off of that. He fed off it in the right way, stayed focused, stayed locked in.
Mayfield (in 2016): That's exactly how I thought it was going to be and I enjoyed it.
Keke Coutee, Tech receiver: I knew the game was going to be a barn burner, because Baker had a lot to prove leaving Tech. Then Pat was such a competitor. Guy's a baller.
Stoops (this week): After watching Mahomes on tape. I was like, 'Oh my gosh, this guy can make any throw from any angle.'
Mayfield (this week): The physical attributes that Pat has -- he has everything you could possibly want. His arm strength is unbelievable, but just the different arm angles and things he is able to do -- I know people talk about his no-look passes and all of that - but to be able to change his arm angle, you can see why he was such an incredible athlete in baseball and basketball, as well. He's just able to do things that a lot of quarterbacks can't do.
Drew Krueger, Tech trainer: Pat injured the shoulder against Kansas [three weeks before]. It was a significant shoulder separation. Those are very painful for any type of movement, not to mention throwing the football. He played against Kansas State, and then on the last play, he fell on it again. So it was real sore and we were all kind of unsure what to expect.
Kingsbury: He had been limited in practice. They had to numb his shoulder before the game, and then he broke his [non-throwing] wrist in the first half. Nobody knew it. He just kept playing and ended up having to get surgery after the season, before the combine and bowl prep.
Krueger: He just asked us to tape it up.
Brian Jensen, Tech play-by-play voice: [Level] kept telling us you could see it in his face, the pain he was in. He was fighting through it all.
Level: Just a total warrior.
Obo Okoronkwo, OU linebacker: Patrick had the juice the whole game. He didn't get tired. Like, he never looked tired the whole game.
Kingsbury: He was so locked into the zone, and they had the same thing going on.
Both offenses were loaded beyond just the quarterbacks. Along with Mayfield, OU wideout Dede Westbrook was a Heisman finalist that season, and left tackle Orlando Brown Jr. and tight end Mark Andrews would become unanimous All-Americans the following year. Joe Mixon is now the starting running back for the Cincinnati Bengals, and on the Tech side, Keke Coutee would go on to become a starting receiver for the Houston Texans.
Mahomes: They had a ton of talent. We had a ton of talent.
Rick Trice, Tech statistician: We're used to having a lot of offensive numbers here, but we were not prepared for the way that game would play out.
Kingsbury: I think there was anticipation there could be some fireworks. ... Look at some of players you had in that game. You look at Baker and Joe Mixon, Dede Westbrook lighting it up. Plus the big tight end [Andrews] that's at Baltimore. And then we had Pat and Keke Coutee on our side going up and down the field, spectacular players. And then two quarterbacks, Baker obviously with the history here. He was on a mission, and then Pat was on a mission of not letting him get one here.
Riley: Most of our stuff was on schedule. Mahomes was a little different. ... making so many unconventional plays, so many plays off script, coming out of rushes, big scrambles, throwing going sideways. He just made some unbelievable plays. And that kept them in it. You knew you were watching something pretty special with the way those two guys were playing.
Stoops: I vividly remember us a couple of times having our hands on Patrick, really feeling that hey, we finally got a sack. A chance to turn it for us. And he would pull out of it somehow, escape the sack and fight his way out of it.
Okoronkwo: We had him in our hands at least 10 times and he just kept slipping out of there, like he was greased up or something. There were a lot of times I was pursuing him where I thought I was going to get him and I didn't. We couldn't stop him.
Teddy Lehman, OU color analyst: Mahomes' performance was maybe more impressive than Baker's in a sense, because he was scrambling for his life. And I hadn't seen another player we've played that was throwing guys open. He would scramble and just throw it to a spot and his receivers would make adjustments to come back to the ball.
Mahomes proves unstoppable
In addition to the quarterbacks, multiple players in this game would put up monster numbers. The Red Raiders would nearly have three different receivers go over 100 yards in Coutee (172), Jonathan Giles (167) and Cameron Batson (99). The Sooners, meanwhile, would become the first team in FBS history to boast a 500-yard passer, a 200-yard receiver (Westbrook) and a 200-yard rusher (Mixon), who would become the first player in OU history to finish with 200 yards rushing and 100 receiving in the same game.
Riley: Joe Mixon had a touchdown run called back for a holding penalty. It still, to this day, might be the best run I've ever seen in college football. He just kind of wiggled his way, reversed field, ended up breaking several tackles. He caught a ball one-handed up the right sideline for a touchdown. He was fabulous that night, one of the best individual running back performances I've ever seen.
Jensen: The guy that really killed us was Mixon. Granted, Mayfield threw well, he had seven touchdown passes, but Mixon would be wide open, break a tackle and be gone.
Level: We still talk about this game quite a bit. For OU, it was the Joe Mixon/Dede Westbrook show.
Jah'Shawn Johnson, Tech safety: Those skill guys they had were tremendous. Baker did a great job buying time and putting it on the money all night.
Four minutes in, it looked as if OU was on its way to a rout. Giles fumbled the ball away on Tech's first possession, and Mayfield hit Westbrook for the Sooners' second touchdown. Then Mahomes faced third-and-long from deep in his own territory.
Riley: Baker probably wanted to win that game as much or more than any we ever played here. I knew he was really, really locked in. He threw two early touchdown passes that I think kind of settled him in.
Mayfield (in 2016): I let them know very quickly we were not going to flinch.
Jensen: Pat had a third-and-10 from his own 16. And here comes Pat with a pass to Cameron Batson [for 31 yards]. Just suddenly you could see it in his demeanor, the team's demeanor -- "OK, here we go."
Level: Kliff decided to say screw it, we're just not going to run the ball.
Riley: It was frustrating because we got to a number of third downs and could not get them off the field, and Mahomes was such a big reason why.
Jensen: Every time Pat would put a drive together, they'd get a gut punch a couple of plays later from Oklahoma. Oklahoma scored so fast on their drives, they weren't really even drives. And then Pat would have to put together something to come back. It was just ridiculous that he kept coming up with another play.
Riley: We hit so many big plays offensively that our play numbers weren't just incredibly high.
Kingsbury: We had the lead and they hit a long pass right before halftime to take it back. I knew it was going to take 60 points to win this thing.
Johnson: It was very frustrating. All we needed was one stop, the way our offense was rolling. But they weren't going to be stopped.
Orlando Brown Jr.: I don't mean to talk bad about Tech, but they didn't have a lot of talent defensively. Our mentality was score as much as we can.
A classic unfolds
Both offenses were hot in the first half. In the second, they were completely unstoppable. After Tech punted to open the third quarter, the two teams scored touchdowns on every drive the rest of the game for a total of 10.
Mayfield (that night): I told some of the guys at halftime, "If you're scared and you don't want to score every drive, then stay in here."
Riley: I honestly think people couldn't really believe what they were seeing.
Trice: In the third quarter, I started really keeping track of the total offense for both teams and looking at it constantly and actually updating the media relations department because I felt we were probably creeping up on NCAA records.
Kingsbury: I've never seen anything like it. Pat was phenomenal, and [Mayfield was] on the other side. I don't know if the ball touched the ground for them the entire night.
Johnson: Those guys were going at it, making plays left and right. It wasn't pleasant for the defenses.
Andrews: Our fullback Dimitri Flowers ran an out route and turned it up. Baker started scrambling around and found him in the back of the end zone [for a 34-yard touchdown late in the third quarter]. It was such an incredible catch. One of those things that you don't see very often.
Lehman: A crowd gets into a game whenever the defense is trying to get a big stop. But there were basically never any. So there were never these moments where the crowd got really loud. It was the weirdest thing.
Creighton DeKalb, OU band (drums): The "Boomer Sooner" count actually wasn't abnormally high. We play Boomer between plays to encourage the team. But the offense scored so fast, we really only got to play it after touchdowns.
Lehman: There was a lot of standing around waiting for kickoffs to happen.
Level: It was like pingpong. I don't know if Oklahoma was ever in danger of losing that game. But Pat kept slinging it. He would not go away.
Trice: You knew in the second half that if either team made a hiccup, had a turnover, had to punt, whatever, it was going to cost them the game.
Andrews: Greatest game I've ever been a part of. Two great, prolific offenses going after it. Everybody knew that we were going to score. The whole time the feeling was the last team with the ball was going to win.
The records start falling
Turned out, that would be the case. But not before an array of spectacular fourth-quarter plays -- some of which the Red Raiders had to devise from scratch.
Kingsbury: You just run out of plays. When you're calling that many plays -- and that many pass plays -- you're drawing stuff up in the dirt and trying to get people open at the end of it.
Mahomes: With Coach King, we always had plays left in the tank.
Kingsbury: I just remember asking Pat on the sideline, "Hey, would this work because I don't have much left on the sheet? So what do you think?" And he usually had good answers. We'd come up with something, and no matter what we called that night, he was gonna make it work.
Stoops: Coach Riley came up to me at a certain point -- I want to say early in the fourth quarter -- and asked me did I want him to burn the clock. I said, "Listen man, we need to score. We're not making enough plays [on defense], and [Mahomes] is hot and we got Baker." They weren't stopping us, so I said, "Look, you just do what you got to do to score and don't worry about the clock."
Kingsbury: Pat threw a pass falling off his back foot. The ball probably went 60 yards to Keke with a rusher barreling down right in his face. I didn't think he'd ever get it there, and he hit him in stride. One of the more impressive throws I've ever seen.
Mayfield: He does stuff that you can't even think of being possible.
Jensen: "Can you believe he just did that?" I must have said that a thousand times in his career, but during this game in particular.
Coutee: It went quick, but at that point I thought we were actually going to win.
Stoops (this week): I was just glad we had Baker with us, that he could keep answering.
Jensen: My voice was terrible. It was raspy and weak and I was drinking everything I could get my hands on in the booth. Water and Diet Cokes. I stuck in ice, doing everything I could do just to keep it going.
Mahomes: I think baseball had me prepared from being a pitcher. I didn't know I had thrown that many times. I remember one of my buddies [receiver Hunter Rittimann] came up to me before the last drive and was like, "You have 77 pass attempts right now," and I was like, "Man, that's a lot of passes."
Chad Harberson, Tech push-up guy, tasked with doing one to match the Red Raiders' score after each touchdown or field goal: It was insane. We were dead there at the end. Those guys holding up the pushup board, they were exhausted. We were dreading that next set we would've had to do if Tech had tied it up at the end. But it would've been well worth it.
After cutting OU's lead to 66-59 with 1:38 to go on a 3-yard touchdown pass to Batson, Mahomes wouldn't touch the ball again.
Riley: The last play of the game, other than when we kneeled it, we had a third-and-short, had to get a first down. We were up seven, had to get a first down or we'd give them the ball back and certainly didn't want to do that.
Andrews: It was complete exhaustion. There were so many plays, so many catches, so many everything.
Riley: You're just kinda like, "Wow, that was a marathon."
Trice: The craziest thing about the game is that both teams had exactly the same number of yards . I don't even know how that happens.
Kingsbury: I was actually walking to the locker room and SportsCenter was already playing it. I saw the yardage and the numbers and I'm like, "Wow." To have both those guys play the way they did. ... We'll never see it again, I don't think.
Riley: For so many years [as a Tech assistant under Mike Leach], I walked up the other tunnel after the game. The first time being on that side of it was kind of an eerie feeling. I was just finally taking it all in, what really just happened, being able to be a part of those two offenses and their historic performances.
The legend of Mayfield and Mahomes begins
Covering the game that night at Jones Stadium for ESPN, I was in the visitors tunnel afterward. Mayfield stopped by to casually rehash the game, asking what records Mahomes had broken. Like most everyone else, he too had been blown away with Mahomes' performance.
Jensen: It was the game that really stamped in our mind how great Mahomes was and was gonna be. There were so many times he could have faltered in that game and he never did. I'll never forget how impressive he was in that game.
Coutee: What he was able to do that night was remarkable.
Krueger: He is probably the toughest athlete I've gotten a chance to work with that closely. I think we were just amazed at what he was doing after all his injuries, because he really rose his level of play after a couple of bad weeks dealing with the shoulder. He was unstoppable.
Kingsbury: He was going to try and will that game no matter what. I wish we could've won the game for him because he deserved that.
Mahomes: It was a game where there were a lot of talented people on the field, one of those Big 12 shootouts. I wish we would have won, but it was just awesome to be a part of it.
Riley: I've always had a lot of confidence in Baker and his ability. I always thought he would have a chance to be an excellent pro. I left that night feeling the same way about Mahomes.
Plank: Everyone that left that stadium that night, even if they were the most die-hard haters of Baker Mayfield, couldn't help but come away impressed with what they witnessed.
Johnson: That's why Baker went No. 1. He protects the ball very well and gets the ball to his playmakers. That's why Pat went top 10 as well. He extends plays with his feet and can make any throw.
Mayfield: Talent-wise, I thought he should've been [a No. 1 pick, too, in 2016]. I love Myles [Garrett, Mayfield's Cleveland teammate, a defensive end out of Texas A&M who was actually the No. 1 pick that year]. Coming from the Texas Tech system, there are always your skeptics about people doubting the fact that all he did was sit back there and throw the ball. He threw it 88 times in our game, but when it comes down to it, throwing the ball is throwing the ball, and he is really good at it.
The aftermath: Exhaustion, appreciation
Immediately afterward, part of the focus nationally was on the defenses, instead of the incredible offenses. But as Mahomes and Mayfield have gone on to NFL stardom, the 2016 OU-Tech game has come to be appreciated for what it truly was -- a quarterbacking classic.
Rowland: When I was calling it, I was thinking in my head, "We're seeing the most amazing college football game of all time. These two teams are just trading haymakers." Then as soon as you get on social media, the outcry of anger that people who watched it, they didn't feel that way. They were mad because the defense was so poor.
Lehman: I've never seen a locker room where it honestly looked like half of the guys won the Super Bowl and half of the guys, like, lost to Rutgers.
Okoronkwo: It felt like we lost. Yeah, we won the game, but we gave up  yards. It was quiet, we didn't say nothing on the bus ride home. We were ashamed. Everybody was laughing at us. I looked at my Twitter, and I just deleted the app off there because all our fans were disgusted with us.
Riley: It wouldn't have mattered that night really what defense was out there. I think a lot of people that saw the numbers and the score after the game and didn't watch it missed out. It was a great college football game.
Kingsbury: It was just the perfect storm for that type of offensive output. I remember afterward thinking that I was really fortunate to be able to work with both those guys at one point because it was the highest level of quarterback play I've ever seen in college going at each other. A surreal experience for me.
Mayfield: Weird things happen in Lubbock, Texas, on Saturday nights.
Okoronkwo (this week): The best and second-best quarterback performance I've ever seen in person, and both of them were in that game.
Stoops: I definitely felt we were watching two guys that would be playing on Sunday.
Kingsbury: That night, those two did it as good as you could ever do it in college.
Riley: I've seen a lot of good offensive performances over the years, and the way those two quarterbacks played that night, they'd score on anybody. The people there that saw it, they ought to consider themselves lucky. Because chances are, they'll never see anything like it again.
ESPN's Lindsey Thiry, Jamison Hensley, Sarah Barshop and Adam Teicher contributed to this report.