Punting from Georgia's end zone, Butler had to rush the kick and left Mathieu's with plenty of room to find a lane.
Mathieu raced 62 yards for the Tigers' first score of the game.
"It was just poor execution on my part," Butler said. "I just wanted to get it out there and get the kick off. I left my guys out to dry for sure."
Mathieu's struck again in the third quarter. He returned a punt 47 yards to the Georgia 17-yard line.
"What it came down to is me trying to do what I can for my team," said Mathieu, who also recovered a fumble.
LSU scored three plays later, extending its lead to 21-10.
"It's inexcusable with a guy like him back there," Butler said. "He deserves a lot of respect as a return man. You can't be putting your guys out there with that much ground in front of him. He's just too good of a returner."
Butler otherwise had a record-setting night in the 42-10 loss. His 51.7 average per punt was an SEC title game best. A 62-yarder in the first quarter was the fourth-longest punt in the game's history.
However, Mathieu's two plays erased about good thoughts about the punting unit's performance.
"There's something about him that he seems to find a way to do something special just about every game, and he did it again," coach Mark Richt said.
INJURIES STRIKE TAILBACKS
Matchups or fatigue didn't dictate which Georgia running back played on a specific down Saturday. The rotation was more a matter of who could physically play.
Freshman Isaiah Crowell limped and hobbled on his still recovering sprained left ankle for most of the first half. "I mean, I'm not 100 percent," said Crowell, who finished with 15 yards on 10 carries.
Carlton Thomas was unable to finish the game after suffering a knee injury in the third quarter.
"It was a tough play, and I really banged my knee up with guys falling on it," Thomas said. "I think it's an MCL sprain right now, but I'll try to get ready for the bowl game."
Richard Samuel IV was unable to play four weeks removed from foot surgery.
The injuries nixed any chance for consistency at the position. Thomas has 28 yards on seven carries. Redshirt freshman Ken Malcome led the team with 37 yards, all coming in the fourth quarter.
"(Malcome) ran extremely hard," Richt said. "I was proud of him."
The Bulldogs averaged 2.3 yards per rush.
"Injuries are no excuse right now," Thomas said. "It's a tough game and you're going to have nagging injuries. This is the SEC. You're going to have tough opponents and take big hits."
While Georgia led at halftime, there were opportunities missed that could have built an even greater lead.
"We were knocking on the door," quarterback Aaron Murray said. "I can say that. We were driving and were close to scoring a couple of times."
Junior receiver Tavarres King had a pass from Murray go through his hands in the end zone on the offense's first drive of the game.
The Bulldogs settled for a 40-yard field goal by kicker Blair Walsh.
On the next series, freshman wideout Malcolm Mitchell had a sure touchdown fall from his grasp. Mitchell stared into the crowd for a couple seconds, frozen in place by his mistake.
"I was trying to run before the catch," said Mitchell, who had four catches for 32 yards.
Walsh missed a 45-yard attempt on the next play.
Later in the first quarter, junior cornerback Sanders Commings let an interception go through his hands deep in LSU territory. Had Commings made the pick, a touchdown was likely.
All the dropped chances allowed LSU to hang in the game and left Georgia's players wondering if an upset would have happened with a different outcome on a few plays.
"It was tough because you always want to get seven points," Mitchell said.
THIS AND THAT
The 42 unanswered points by LSU in the second half is the most in SEC Championship game history. … Junior linebacker Mike Gilliard left the game in the third quarter with a right ankle injury. … LSU backup quarterback Zach Mettenberger, who was dismissed from Georgia in 2010, hugged and spoke with former teammates and coach Mark Richt prior to pre-game warm-ups.