ESPN College Football

A stifling defense has led LSU to the nation's No. 1 ranking during perhaps the best start in school history.

The Tigers, however, are about to find out how they'll fare without that unit's biggest star.

Cornerback Tyrann Mathieu is among three LSU players suspended for Saturday's matchup with No. 19 Auburn, which has chosen Baton Rouge as the daunting destination for quarterback Clint Moseley's first collegiate start.

Mathieu has gotten some Heisman Trophy buzz for his dominating season, which has included four forced fumbles, two interceptions, 42 tackles and 1 1/2 sacks.

He's perhaps the biggest reason LSU (7-0, 4-0 SEC) is fourth in the FBS in total defense at 251.9 yards per game, seventh in scoring defense at 11.7 points and tied for 11th in interceptions with 10. The Tigers have won each of their first seven games by a double-digit margin for the first time in school history.

But Mathieu, running back Spencer Ware and defensive back Therold Simon won't suit up Saturday because they've run afoul of the team's drug policy. Ware leads LSU with 512 rushing yards and seven total touchdowns.

LSU, seeking its first 8-0 start since the 1973 team won its first nine, has already managed to stay unbeaten while dealing with suspensions.

Quarterback Jordan Jefferson missed the first four games of the season, including matchups with Oregon and West Virginia, after he was involved in a bar fight, and receiver Russell Shepard missed the first three contests because of an NCAA rules violation.

LSU may be able to overcome this week's absences in part because -- for the third consecutive week -- it will be facing a quarterback making his first start of the season. The previous two, however, were based on injuries, while Moseley was chosen by Auburn coach Gene Chizik to replace Barrett Trotter.

Freshman Jacoby Brissett replaced an injured John Brantley for then-No. 17 Florida on Oct. 8 -- and found little success. LSU limited him to 8 of 14 passing for 94 yards with a touchdown and two interceptions in a 41-11 win.

Last Saturday at Tennessee, the Volunteers were without Tyler Bray because of a thumb injury and Matt Simms struggled in his place. LSU allowed Simms to go 6 of 20 for 128 yards and two interceptions in a 38-7 victory.

"They're an amazing defense," Moseley said. "There's no way around it. It's something that you really do dream about. I mean, how much more dramatic could it possibly be: No. 1 team in the country, road game, huge underdogs. It doesn't get any better. It's an opportunity I've dreamed of forever."

Trotter started the first seven games for Auburn (5-2, 3-1) but was lifted at halftime of last Saturday's 17-6 win over the Gators with his team leading 7-6. The junior had gone 2 of 8 for 33 yards and was coming off an uninspiring performance in a 38-14 loss at Arkansas the previous week, when he went 6 of 19 for 81 yards.

Moseley, who had attempted only two passes before coming in against Florida, showed a bit more composure in the pocket, going 4 of 7 for 90 yards.

"The game was a little fast for me at first," the sophomore said.

Moseley does have the benefit of being joined in the backfield by Michael Dyer, who ranks third in the SEC in rushing with 752 yards and eight touchdowns.

As a freshman last season, Dyer ran for 100 yards on 15 attempts while teammate Cam Newton rushed for 217 yards in then-No. 5 Auburn's 24-17 win over No. 6 LSU, snapping a three-game losing streak in the series.

LSU has won five straight at home over Auburn since a 41-7 loss in 1999, and 14 in a row at Tiger Stadium overall since a 13-3 loss to then-No. 1 Florida on Oct. 10, 2009.

Like its last few opponents, LSU has done some shuffling of its quarterbacks, but that has been more by design. Coach Les Miles has been using both Jefferson and Jarrett Lee since Jefferson returned.

Against Tennessee, Lee started and completed 13 of 17 passes for 138 yards and three touchdowns, giving him 11 TD passes with one interception this season. Jefferson gave the Vols' defense a different look when he entered the game to run the option, finishing with 73 rushing yards on 14 attempts.

"I liked using both quarterbacks," Miles said. "I think that's what's best, what we need to do. I think both guys can do different things, and we like to do that. We will continue to do that. There is a want for both guys to have success."

Jefferson and Lee both struggled against Auburn last year, combining to go 15 of 28 for 89 yards and an interception, although Jefferson ran for 74 yards and a touchdown.

The duo faces an Auburn team that ranked 105th out of 120 FBS schools in total defense before holding the banged-up Gators to 194 yards.