LSU carried its heavily discussed remaining "fight" into the first quarter at Ole Miss.
But the Tigers (4-4, 2-3) appeared to be running on close to empty well before halftime, while the No. 12 Rebels (6-1, 3-1) were only starting to gain their own steam en route to a 31-17 victory.
"We were doing a good job at first," senior linebacker Damone Clark said. "But like I say each time I do interviews, we've just got to finish. That's the biggest the thing we have to do is just keep finishing."
Coach Ed Orgeron's team forced a pair of quick punts from its hosts to start the game and meanwhile marched 90 yards in nine plays on its own first possession for a 7-0 lead.
Sophomore quarterback Max Johnson completed his first four passes to three different receivers for 71 yards.
And junior running back Tyrion Davis-Price took his fifth carry across the goal line for his 19th and final yard of the march.
But subsequent drives of 72 and 38 yards stalled to the tune of a fourth-down, goal-line interception late in the first and missed 55-yard field midway through the second.
"I know our guys came to fight," Orgeron said. "We had a good week of practice. We didn't capitalize in the first half. Fourth-and-1 hurt us, not capitalizing on that. We knew we had to score points."
Coach Lane Kiffin's Ole Miss offense seized the opportunity to rattle off 31 unanswered points during the second and third quarters.
Mandeville native Caden Costa put the Rebels on the board with a 43-yard field goal early in the second quarter.
And following LSU's missed kick the next possession, Heisman hopeful Matt Corral and the Rebels were off to the races for four touchdowns over the next five possessions.
The junior quarterback found sophomore tight end Casey Kelly from 2 yards out for the first score to cap a 63-yard drive, then finished an 80-yard drive with a 3-yard run of his own.
And the running back duo of Henry Parrish Jr. and Jerrion Ealy added third-quarter runs to the end zone of 5 and 36 yards, respectively.
"It's no excuses," said Clark, who finished with 20 tackles for the Tigers, including 2.5 for loss and a sack. "We've just got to go out there and execute. It's the SEC. Each week you're gonna see a team like this. And, like I said, you've gotta go out there and execute. There's no excuses for anything."
Corral finished 18-for-23 for 185 yards and the one passing touchdown and rushed 12 times for 24 more yards and another score.
Junior running back Snoop Conner led the ground game with 14 carries for 117 yards. Ealy and Parrish added 97 and 32, respectively, plus a score each.
"I didn't think we won the line of scrimmage," Orgeron said. "We jumped out of our gaps in run discipline. We ran the ball for 77 yards. They ran for 266. I think that's the story of the game."
LSU added 10 fourth-quarter points on a 47-yard Cade York field goal and 9-yard dart from freshman quarterback Garrett Nussmeier to freshman wide receiver Malik Nabers.
But the Rebels safely secured the Tigers' ensuing onside kick attempt and ran the clock from there.
Johnson finished 13-for-21 for 146 yards and an interception before being relieved by Nussmeier, who completed seven of 12 attempts for 102 yards and the score.
Junior receiver Jaray Jenkins, freshman Jack Bech and Nabers each caught four passes for 52, 41 and 30 yards, respectively.
Davis-Price rushed 17 times for 53 yards, and freshman running back Corey Kiner added 49 yards on 10 attempts.
"We got behind on the chains," Orgeron said. "I think we didn't have the success, the big runs, and just got behind the chains a little bit and tried to throw the football. Plus we got behind. In the first quarter, we were just taking out time. We wanted to keep the ball away from them. I thought we did a good job of that. But then we couldn't capitalize when we needed to."
LSU enters its bye week before traveling to No. 4 Alabama (6-1, 3-1).