Each also saw his win streak come to an end during his most recent outing.
Miller had his seven-bout winning streak halted by Benson Henderson in August. Guillard had won five in row before facing upset-minded Joe Lauzon in October.
So Miller and Guillard stepped into the Octagon on Friday night in Nashville, Tenn., determined and confident of righting his ship.
Guillard would get off to a fast start, landing hard knees and punches. It appeared early that Miller would have trouble surviving Guillard's speed and striking power.
But there was no quit in Miller. When Guillard left himself open after throwing a knee, Miller took him to the ground.
Miller would get Guillard's back and apply a rear-naked choke. Guillard was unable to escape and tapped at 2:04 of the first round.
"I don't get knocked down often and he knocked me down. He hits hard," Miller said after improving to 21-3. "There are a lot of people in this weight class and probably the one above who don't want to fight that kid.
"I just find a way to the back. That's something that I've always been able to do. I am confident that I am the most dangerous lightweight in the world. I'm willing to make you guys believe that in here [the Octagon]."
Guillard suffers his second loss in a row, both coming via a rear-naked choke in the first round. His professional record now stands at 29-10-2 with one no contest.
Neer eats punches, submits Ludwig
But Neer never backed away and eventually got the fight to the ground, where he was able to apply a guillotine and choke out Ludwig.
The finish came at 3:04 of the opening round.
"It's a good win," Neer said. "I wanted to stand up and trade more, but he was getting the better of me. I wanted to take it to ground and finish him."
Neer extended his win streak to six, while improving to 33-10-1.
Ludwig's win streak stops at two. He slips to 21-12.
Easton edges newcomer Papazian
Mike Easton and Jared Papazian shared ill wishes toward one another before the start of their bantamweight fight. And each promised to win by knockout.
The knockout did not materialize, but onlookers weren't disappointed. Easton and Papazian went and delivered strikes at a high pace for three rounds.
And after the judges submitted their cards, Easton had a majority decision.
The judges scored the fight 29-28, 30-27 and 29-29. ESPN.com had Papazian winning 29-28.
Despite their prefight hostility, Easton and Papazian hugged after the final horn sounded.
"He's a tough dude," Easton said after improving to 12-1. "I knew he was going to be tough."
Papazian, who fought for the first time in UFC, had his win streak end at three. He is 14-7 with 1 no contest.
A Barry left hook KOs Morecraft
Heavyweight Pat Barry regularly makes it known that he enjoys putting on an exciting fight. But with a two-fight losing streak hovering over his head, Barry was eager for a win against Christian Morecraft.
Barry got the win he wanted and did so in emphatic fashion -- landing a left hook in the first round to knock out Morecraft at 3:38 of the opening round.
While the finish was impressive, Barry had difficult moments early in the round, especially on the ground. Morecraft took him down several times, and nearly finished the fight with an armbar.
But Barry escaped and got to his feet, where he would eventually hand Morecraft his second straight setback.
"I'm sorry that took me nine getting choked out experiences, I'm sorry," said Barry, who improved to 7-3. "My bad. I'm counting.
"I'm all or nothing, all the time. My confidence is always through the window."
Morecraft falls to 7-3.
Rivera goes out a winner
Rivera got his wish, stopping Schafer at 1:31 of the second round to end his professional career with a record of 20-9.
"I'm grateful to have fought in front of a lot of people," a very emotional Rivera said. "I've met a lot of nice people. It's been a real nice trip; it's been real good to me. I'm extremely thankful."
Schafer slips to 12-7-2. He has lost two fights in a row.
Nurmagomedov submits Shalorus in third
Khabib Nurmagomedov was undefeated as a professional when he entered his lightweight bout against Kamal Shalorus. He'd also never fought inside a cage.
But none of that mattered as Nurmagomedov used a left uppercut to control the standup and solid takedown skills to get Shalorus on the ground.
In the third, Nurmagomedov took Shalorus (17-0) down and applied a rear-naked choke to secure a win in his UFC debut. Shalorus (7-2-2) tapped at the 2:08 mark.
Camoes submits Hayden in UFC return
Nearly two years since he last appeared in UFC, lightweight Fabricio Camoes made his return to the Octagon a successful one.
In a first round that was fought mostly standing, Camoes eventually got it to the ground and secured the back of newcomer Tommy Hayden.
Camoes (14-6-1) was able to apply a rear-naked choke and force Hayden (8-1) to tap at 4:03.
Pineda submits Schilling in first round
Featherweight Daniel Pineda wasted little time proving he belongs in UFC, submitting Pat Schilling via rear-naked choke at 1:47 of the first round.
It was Pineda's first appearance inside the Octagon. He improved to 16-7, while extending his win streak to six.
Schilling, who also made his UFC debut in this bout, suffers the first loss of his brief professional career. He is now 5-1.
Denis registers a knockout in his UFC debut
Nick Denis did not spend much time inside the Octagon during his UFC debut. He went after Joseph Sandoval immediately, landing several elbows to register a first-round knockout in a bantamweight showdown.
The bout was stopped 21 seconds into Round 1.
Denis improved to 11-2, while Sandoval falls to 6-2.
Franklin McNeil covers MMA and boxing for ESPN.com. He also appears regularly on "MMA Live." Follow him on Twitter at http://twitter.com/Franklin_McNeil.