BATON ROUGE, La. -- This will become a familiar scenario for No. 15 LSU (4-1, 0-1 SEC) for at least the foreseeable future. Entering Saturday's game against No. 5 Auburn (4-0, 1-0), LSU probably can't afford another division loss if it wants to remain in contention in the SEC West -- much less a spot in the inaugural College Football Playoff.
That's a tall order this weekend, considering Auburn hasn't lost at Jordan-Hare Stadium since Gus Malzahn became coach last season (11-0) and LSU will have a true freshman quarterback, Brandon Harris, making his first career start.
LSU has won six of the past seven games in this series, but getting a win Saturday will be a major challenge. Let's look at three key factors as kickoff approaches, with some help from ESPN's Stats & Information group:
Who can run and who can stop it
Both starting quarterbacks -- Harris and Auburn's Nick Marshall -- are understandably getting plenty of attention ahead of this game. But it's the teams' respective running games -- and whether the defenses can slow them -- that might be the most important factors.
Auburn ranks 17th nationally with 260.5 rushing yards per game and boasts two of the SEC's most productive runners in Cameron Artis-Payne (86 carries, 468 yards, 5 touchdowns, fourth in the SEC with 97.2 YPG) and Marshall (42 carries, 273 yards, 2 touchdowns).
Meanwhile, LSU has struggled against the run, ranking 12th in the SEC and 70th nationally by allowing 161.6 rushing YPG. Coordinator John Chavis' defense is thin at defensive tackle, and its problems there were evident against Mississippi State, which rushed for 302 yards against LSU two weeks ago. Wisconsin also rushed for more than 250 yards against LSU.
Auburn is 13-0 when it runs for at least 250 yards under Malzahn and 3-2 when it does not.
On the other side, LSU's struggling run game got a boost last week when it picked up 363 yards on 54 attempts against New Mexico State. LSU is sixth in the SEC with 226.2 rushing YPG, but Auburn has been stingy against the run (third in the SEC with 90.8 YPG). If coordinator Ellis Johnson's defense is able to shut down Leonard Fournette (LSU's leading rusher with 322 yards on 56 attempts, 64.4 YPG), Kenny Hilliard (57 carries, 298 yards, 59.6 YPG), Darrel Williams (33 carries, 165 yards, 41.2 YPG) and Terrence Magee (34 carries, 144 yards, 28.8 YPG), that will place even more pressure on Harris' shoulders.
Defending the zone read/QB run
Let's dig a little deeper into the running game. To have any chance on Saturday, LSU must contain Marshall and Auburn's option runs.
Auburn has been one of the nation's most effective teams at using the zone-read run since the start of last season. It is averaging 144.39 rushing yards and 6.8 yards per carry in those games.
It's worth noting, however, that Kansas State kept itself in the game against Auburn two weeks ago by slowing Marshall and the zone-read runs. The Wildcats held the Tigers to just 62 yards and 3.1 yards per carry off the zone-read, holding them below 200 total rushing yards for only the second time in Malzhn's tenure as Auburn's coach.
LSU was atrocious against the zone-read in its 34-29 loss to Mississippi State two weeks ago. The Bulldogs ran 20 times for 192 yards from that look, averaging 9.1 yards per carry and breaking five runs of at least 10 yards.
The key element here is slowing Marshall, but LSU has struggled to do that against mobile quarterbacks. LSU has allowed the sixth-most rushing yards to opposing quarterbacks (56 carries for 260 yards) of all FBS programs this season. That includes a 79-yard touchdown last week against New Mexico State and a 56-yard run by Mississippi State's Dak Prescott.
Marshall has 1,341 rushing yards since the start of last season, which ranks third among active FBS quarterbacks.
Harris vs. Auburn pass defense
This subject has been beaten to death all week, but Harris is in rare air for an LSU quarterback. He's the first LSU true freshman to start at the position since Jordan Jefferson in 2008 and the first since Jamie Howard in 1992 to start by Game 6.
He clearly outplayed Anthony Jennings against Mississippi State and New Mexico State, but both of those outings were off the bench. Making his first road start against a better-than-average Auburn defense -- Johnson's defense is fourth in the SEC in total defense (313.2 ypg) and sixth in scoring defense (16.2 ppg) -- won't be easy.
However, Auburn has yet to face a prolific passing team. Its opponents thus far rank 107th nationally (Arkansas, 167.8 ypg), 62nd (San Jose State, 243.0), 59th (Kansas State, 246.3) and 55th (Louisiana Tech, 248.4) in passing offense and yet Auburn still ranks seventh in the SEC in pass defense at 222.5 ypg.
We'll see whether Harris can settle his nerves enough to exploit it, but Auburn is vulnerable against the pass -- especially if veteran safety Jermaine Whitehead remains on suspension for a third straight game.