ATLANTA -- With Jeremy Johnson taking over at quarterback, No. 6 Auburn looked a bit sluggish on offense.
Fortunately for the Tigers, Will Muschamp's revamped defense came up with a couple of huge plays.
The former Florida coach made his debut as Auburn's defensive coordinator, charged with turning around a unit that fell apart late last season. The first half of the opening game was promising, with an interception leading to the Tigers' first touchdown and Justin Garrett scoring on an 82-yard fumble return.
"I am very excited about this season and what the defense can do," tackle Montravius Adams said. "We forced a lot of turnovers and got a lot of sacks. That shows people we are getting better."
Even though he spent the last two years behind Nick Marshall, Johnson came into the season hyped as one of the potential breakout stars in coach Gus Malzahn's explosive spread offense.
The junior completed only 11 of 21 for 127 yards with three interceptions, though he did throw a 33-yard touchdown pass to Ricardo Louis.
"I just made some mental mistakes," Johnson said. "I'll learn from it."
Peyton Barber, taking over after starter Roc Thomas went out with an undisclosed injury, wound up carrying the bulk of the offensive load in the Chick-fil-A Kickoff Game at the Georgia Dome. The third-year sophomore rushed for 115 yards on 24 carries, more than doubling his career output.
"That meant everything to me," Barber said. "This is what I've been waiting on."
After not naming a starter at quarterback, Louisville pulled a surprise by giving freshman Lamar Jackson the bulk of the snaps over three more experienced players thought to be battling for the job.
Coach Bobby Petrino sent out both Jackson and sophomore Reggie Bonnafon for the first play, a trick formation the team had been working on all week. Bonnafon went in motion but the direct snap was botched, leaving Jackson scrambling to his right. Looking very much like it was his first college play, he simply threw it up, right into the arms of Tray Matthews.
The Auburn safety returned the interception 35 yards to the Louisville 26, setting up Johnson's 1-yard touchdown run.
Bonnafon played into the second quarter before giving way to Jackson for good after a fumbled handoff with Louisville driving gave the Tigers a 14-0 lead. Garrett scooped up the loose ball and took off the other way, with Muschamp running with him nearly stride for stride along the sideline.
"I saw the ball squirt out," Garrett said. "I just tried to pick it up and run back to the house with it."
Jackson did plenty of good things for the Cardinals in his debut. He was only 9 of 20 passing for 100 yards, but led the team in rushing with 106 yards on 16 carries, including a 10-yard touchdown toward the end of the third quarter.
"That freshman quarterback is electric," Malzahn said. "He's going to be tough to deal with."
After Auburn built a seemingly comfortable 31-10 lead with just over 10 minutes to go, Jackson led a couple of late touchdown drives that made the Tigers sweat it out.
"I thought he really did a nice job," Petrino said. "He competed extremely hard. We saw that in practice. Coming into the game, we knew we were going to play him."
Auburn managed to run out the clock after recovering an onside kick, helped a bit by Petrino's decision to call a timeout after a holding penalty on Auburn.
Johnson was picked off twice in the first half by former Georgia safety Josh Harvey-Clemons, who sat out last season after transferring to Louisville. Trumaine Washington had the Cardinals' other interception, the revamped secondary picking right up where it left off last season, when Louisville led the nation with 26 picks.
Malzahn said he was not concerned about Johnson's performance.
"He was trying to force a few things," the coach said. "He made some very good plays to help us win. He's going to be fine."
Auburn led 17-0 at halftime after Daniel Carlson booted a career-long field goal from 56 yards in the final minute of the second quarter. It was the third-longest field goal in school history.
AP college football website: www.collegefootball.ap.org
Follow Paul Newberry on Twitter at www.twitter.com/pnewberry1963
Dabo Swinney wins sledding race at Clemson
Dabo Swinney takes advantage of the snow with a fun sledding race.
Auburn Tigers land second QB transfer in Oregon Ducks' Robby Ashford
Former Oregon QB Robby Ashford, the No. 168 prospect in the 2020 class, transferred to Auburn on Monday.
QB Chubba Purdy chooses to transfer to Nebraska after leaving Florida State football program
The Nebraska Cornhuskers have transformed their quarterback depth chart through the transfer portal, adding former Florida State Seminole Chubba Purdy to a group that includes former Texas Longhorn Casey Thompson.
Alabama Crimson Tide LB Christian Harris says he's entering NFL draft
Alabama linebacker Christian Harris has announced he will enter the NFL draft.
Onetime Clemson football recruit QB Hunter Johnson transfers back to Tigers after career at Northwestern
After four seasons at Northwestern, quarterback Hunter Johnson is transferring back to Clemson -- a rare transfer to Dabo Swinney's program.
Star pass-rusher Nolan Smith returning to Georgia Bulldogs for senior season
Georgia's top-ranked defense won't look the same next season, but it will feature the return of gifted pass-rusher Nolan Smith, who announced Monday that he plans to come back for his senior season.