(4) TCU (8-0) at San Diego State (4-4)

TCU has little margin for error if it hopes to secure a BCS bid, and thanks in large part to its defense, the Horned Frogs haven’t had to worry about any missteps.

Coming off a shutout in their last game, No. 6 TCU looks to stay undefeated when it visits Mountain West Conference rival San Diego State on Saturday.

TCU is undefeated through eight games for the second time since its 1938 national championship and first since 2003, but the Horned Frogs (8-0, 4-0) have other numbers to be concerned with.

TCU also is trying to remain ahead of No. 5 Boise State—which plays Friday night at Louisiana Tech—for a BCS bid. Those schools are currently the only remaining undefeated teams from a non-automatic qualifying BCS conference.

The Horned Frogs remained sixth in the BCS standings following a 41-0 victory over UNLV, its 10th straight going back to last season. The team moved up two spots in AP poll for its highest ranking since 1956.

“I’m exited for our fans,” coach Gary Patterson said. “My job is to make sure the fans don’t get their hearts broken. We need to finish up and do the things we need to do.”

While the Horned Frogs’ postseason bowl fate may come down to the final game of the regular season, they haven’t faced many challenges so far. The team has outscored its opponents 282-89 this season and 123-13 over the last three games.

And they’re still looking for ways to get better.

“We still haven’t played our best game,” said quarterback Andy Dalton, who threw for 178 yards and three touchdowns last week. “We still have a lot of things we can improve on. … We have a lot of potential, hopefully we can put it together soon.”

Though Dalton has been solid, passing for eight TDs over the last three games and 14 this season, TCU’s defense has been incredible all year. That unit ranks first in the nation in 235.8 yards per game and 97 first downs, and third with 11.1 points per game.

“The confidence level and communication on defense in the last three ball games is the best its been since we started with this group in the spring,” Patterson said.

He’s trying to keep his team focused ahead of next week’s home game against No. 17 Utah, the only other team that is undefeated in MWC play. TCU then visits Wyoming before closing the season at home against New Mexico—a combined 2-6 in the conference.

“The biggest thing you worry about is getting through these next three or four ball games without a letdown,” Patterson said. “If you do have one, can you find a way to win? That’s the hard part. It’s just hard to keep up that kind of intensity for so many ball games.”

Surging San Diego State could be poised to pull off an upset. The Aztecs (4-4, 2-2) are coming off their third win in four games after beating New Mexico 23-20 last Saturday.

Ryan Lindley threw three touchdown passes, including a go-ahead score with 7:54 left in the fourth quarter. He finished 22 of 38 for 253 yards, giving the Aztecs back-to-back wins for the first time since 2007. They haven’t won three in a row since 2002.

“Our seniors have done a tremendous job,” coach Brady Hoke said. “For them, that’s why we get excited as coaches to sing our fight song in the locker room. Guys know how we played and what we need to do to get better. It’s great to be at that point right now.”

Lindley has thrown for 1,010 yards and 12 touchdowns in his last three games, completing 63.2 percent of his passes. In his first five games, Lindley threw eight touchdowns and nine interceptions, while completing only 51.1 percent of his passes for 1,132 yards.

TCU has won all four games against San Diego State since beginning MWC play in 2005, including 41-7 last season when the Horned Frogs outgained the Aztecs 498-85.