BATON ROUGE, La. — In order to have a chance to upset the No. 1 team in the nation, mistakes have to be limited, if not erased all together.

Especially on defense.

For as solid as Auburn’s defense was for the majority of the first half Saturday at Tiger Stadium against top-ranked LSU, four first-half penalties and two breakdowns in coverage sunk the visiting Tigers’ upset bid just as it started to set sail.

In all three of LSU’s first-half touchdown drives, Auburn aided the Bayou Bengals by committing back-breaking penalties.

“I said all along, on the road, our margin of error is zero,” head coach Gene Chizik said. “We’re not good enough for negative things to happened to us and consistently overcome it. We had three critical penalties on drives when we were going to get those guys behind the chains, or at least get them in a favorable position. That created points for the other team.”

Twenty-one of them.

Early on the first drive, a substitution infraction on a third-and-4 gave LSU the first down. Later on the same drive, there was a facemask penalty to put LSU inside the Auburn 9-yard line.

Next play, touchdown.

Midway through the second quarter – with LSU leading 7-3 – a bad snap put LSU in a third-and-very long situation. Or at least it looked like it.

On the play, however, LSU quarterback Jordan Jefferson’s facemask was yanked by Auburn defensive tackle Kenneth Carter.

So, instead of it being a must-pass down with Auburn grabbing all the momentum, it turned out to be a first down for LSU on the Auburn side of the 50.

Two plays later, Jefferson hit a sprinting Rueben Randle for a 42-yard touchdown.

LSU 14, Auburn 3.

Then on LSU’s final drive of the first half, Auburn appeared to get a stop on third-and-4 with about a minute to play, forcing an incomplete pass. But a pass interference penalty on cornerback Chris Davis gave LSU a first down at the Auburn 48.

Three plays later, it was Jarrett Lee’s turn to go deep to Randle, hooking up with the wideout for a 46-yard touchdown pass.

LSU 21, Auburn 3.

Halftime.

Ballgame.

“We were talking about it in our meetings: limit the penalties,” Auburn safety Demetruce McNeal said. “They stayed on the field because of penalties. After that, you saw they scored. They capitalized on that. That was a big reason they got 14 points off that with the two big bombs.

“We said all week, we had to eliminate those boys getting big plays. You saw today, they got two and that set the tone.”

For the game, Auburn committed seven penalties for 51 yards. The visiting Tigers also gave up 393 yards of total offense, including 88 yards on those two first-half touchdown passes.

“That was certainly a thing,” Auburn defensive coordinator Ted Roof said. “We knew we couldn’t give up big plays coming in. And we did. That’s how they beat people. They beat people with big plays, and they made some big plays today. We didn’t do a good job eliminating the big plays.”

And until they can, the Tigers are going to continue to struggle.

“(By giving up) those things right now you can’t win doing that,” Chizik said.