Mississippi State defeated No. 6 LSU on Saturday 44-34 to hand a defending national champion its first loss in its opening game for the first time since 1998.

Bulldogs quarterback K.J. Costello passed for an SEC record 623 yards and had five touchdown passes in the win. It was also Mississippi State coach Mike Leach’s first win since taking the reins.

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“I don’t know if any individual could visualize this taking place,” Costello said. “I wasn’t visualizing sitting here breaking records. ... I’m excited about the potential that this offense has because, believe it or not, we did leave a lot on the field today.”

Costello had joined the Bulldogs after injured-riddled seasons with Stanford.

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The Tigers’ Myles Brennan had 345 passing yards and three touchdown passes in the loss.

“We couldn’t stay with those guys,” LSU coach Ed Orgeron said after the game. “Too many missed assignments. Too many guys running free, getting beat one on one. We have to look at whether or not we can cover man to man. If we can’t, we are going to have to play more zone.”

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With the loss, LSU became the first defending national champion to lose its opening game since Michigan in 1998 when it lost to Notre Dame. LSU was also on a 16-game winning streak.

The Associated Press contributed to this report.