BATON ROUGE, La. ó In these kind of games, on these stages, the margin is agonizingly thin. One missed block, one errant throw, one incorrect path on a tackle attempt ó games like these hinge on errors like those, so easily sandpapered over in other games.

There was 10:10 left Saturday at Tiger Stadium, and the place was awaiting a reason to come unglued, to send the cheers of 92,734 up into the night sky. South Carolina quarterback Connor Shaw was running left, escaping a pass rush. He looked downfield, stopped and attempted an off-balance throw, trying to make something out of this third down and 6 at USCís 29-yard line, with the Gamecocks up by a point.

The throw sailed long into free safety Eric Reidís hands. He returned it 29 yards to USCís 22. Death Valley, as they call this stadium, came to life. LSU converted the pick into just a field goal with 6:37 left, but a minute and 34 seconds later, on the first play of LSUís next drive, Jeremy Hill ran 50 yards for a touchdown. And the sea of yellow roared so loud you maybe could have heard them out in the Gulf of Mexico.

Third-ranked USCís undefeated season died here Saturday, 23-21, in a gem of a game against ninth-ranked LSU (6-1, 2-1 Southeastern Conference). It died not only because of Shawís interception, though that was a fatal blow. And though perfection with wins and losses is gone now, this season of hope remains intact for USC (6-1, 4-1).

The Gamecocks, who hadnít been ranked this high since they were No. 2 in 1984, almost sustained their unblemished record. Shaw hit receiver Bruce Ellington for a one-yard touchdown with 1:41 left, cutting LSUís lead to 23-21. But their final drive fizzled as Shaw threw a long pick to end the game.

USCís three-game gauntlet continues next Saturday at undefeated Florida, a game that now looms larger. Regardless of the USC-LSU result, the Gamecocks were still going to be in auspicious position to win the Southeastern Conferenceís Eastern Division. But now, a loss to Florida could knock them out of contention.

The Tigers carved up USC on their first possession of the second half, cruising 69 yards in nine plays and 3:47 to score a 7-yard rushing touchdown and take a 10-7 lead with 11:13 left in the third quarter. Other than an incomplete pass, no LSU play on the drive gained fewer than four yards. A third-and-4 pass at LSUís 37 gained 16, a run on the next play 17. The pass improved LSU to eight of 11 on third down. USCís 30.3-percent third-down defense before Saturday ranked No. 13 nationally.

The Gamecocks answered with a two-yard touchdown run by Marcus Lattimore that put them up 14-10 with 5:11 left in the third quarter. USC got to the 2 because of a pretty 30-yard pass by Shaw, to leaping tight end Justice Cunningham, who had lined up wide. Shaw threw the ball back across the field and dropped it between two defenders.

LSU had an excellent chance to go up 17-13 early in the fourth quarter, after driving from its 22 to USCís 9, where the Tigers had first and goal. But on third and goal at the 3, LSU opted for a Zach Mettenberger pass to the back corner of the end zone, despite the fact that LSU had been running the ball well, with 187 yards on 45 carries at that point. Mettenberger threw it out of bounds, and the Tigers settled for a field goal with 10:17 left. USC still led, 14-13.

The Gamecocks made another admirable stand on LSUís next possession, which started at USCís 22 after Shawís pick, just his third of the year. The Tigers had first and goal at the 11, but had to kick another field goal. It put them up 16-14 with 6:37 left. It was LSUís fifth red zone trip Saturday. At that point, the trips yielded just one touchdown and three field goals.

The nationally televised matchup figured to be a defensive battle. LSU entered the game ranked third nationally in yards allowed per game, USC 11th. And it was just that in the first half, after which USC led 7-3. You got the sense that the second half would hinge on whose defense would crack in the biggest spot, as USC did on Hillís run.

LSU had 178 yards in the first half, to USCís 69, while the Tigers started a redshirt freshman at right guard, in his first start, and a true freshman at right tackle, in his third. But the Gamecocks and their formidable defensive line played its best at the most opportune times in the first half.

On its first possession, LSU drove 69 yards in 16 plays and 7:47, but couldnít crack the end zone despite having first down at USCís 3. LSU settled for a 23-yard field goal and a 3-0 lead. The stand was typical. The Gamecocks entered Saturday having allowed just four touchdowns in 14 red zone trips by their opponents Ė a 28.6-percent clip that ranked fourth nationally.

USCís offense didnít breach midfield until its fifth and final drive of the first half. Lattimore ran 10 times for just 25 yards in the half. And USCís only points should have really been credited to by cornerback Jimmy Legree.

On the penultimate play of the first quarter, he jumped a route and stepped in front of a wobbly pass by Zach Mettenberger, after Mettenberger locked in on his receiver. Legree returned it 70 yards, to the 1. USC needed just two plays to punch it in, with 14:54 left in the first half.

Played in front of a deafening crowd at Tiger Stadium, the game was one of the most significant in USCís history, just as last weekís in Columbia against fifth-ranked Georgia. The Gamecocks were trying to start 7-0 for the second time ever, and the first since 1984, when they began 9-0.

Fourth-ranked Florida did its part to set up an undefeated matchup next week with USC by beating Vanderbilt 31-17 on Saturday. The Gamecocks, riding a nation-best 10-game winning streak, faced an intimidating setting as they attempted to remain unblemished. LSU had won 21 straight home games entering Saturday Ė best in the country.

Few teams win in Baton Rouge on these stages; the Tigers are now 35-1 in Saturday night home games under eighth-year coach Les Miles. The Gamecocks hoped they could break the trend. That they failed to will not define their season, but it makes their response to it all the more important.