Seventeen teams have made it through the first third of their schedules with 4-0 records. Here are five with shots to make it unbeaten through the regular season and five that probably will have their bubbles burst.
First, the ones with a chance:
Why Buckeyes keep winning: The defending national champions, winners of 17 straight, are the most talented team in the country.
Why they might not: If they don't shore up some inconsistencies on offense.
Next tough test: Nov. 21 vs. Michigan State.
Star, so far: Adolphus Washington has played the best on a defensive line stocked with NFL talent.
Why Rebels keep winning: Chad Kelly keeps chucking it for 300 yards a game to a wealth of receivers.
Why they might not: If they're as flat as they were against Vanderbilt, they won't make it through the SEC unscathed.
Next tough test: This week at Florida.
Star, so far: Kelly, the first-year starter, has thrown 10 TD passes.
Why Utes keep winning: A favorable schedule, and fourth-year starting QB Travis Wilson keeps the offense moving like it did against Oregon.
Why they might not: The Utes' defense is stout up front, but the secondary is vulnerable to the big play.
Next tough test: Oct. 10 vs. California.
Star, so far: Wilson has completed 68 percent of his passes and thrown for 4 TDs and run for 67 yards a game and 3 TDs.
Why Irish keep winning: The replacements for the long list of injured players keep performing at a high level, particularly QB DeShone Kizer.
Why they might not: More injuries, and if the secondary keeps giving up big plays.
Next tough test: This week at Clemson.
Star, so far: Kizer, who has started the last four games after being the No. 3 QB in the spring, is hitting 68 percent of his passes with 5 TDs against 2 picks.
Why Bulldogs keep winning: Greyson Lambert comes anywhere close to matching his interception-free, 77-percent passing.
Why they might not: The defense has had a tendency to lose focus at times, and even a brief letdown gets you beat in the SEC.
Next tough test: This week vs. Alabama.
Star, so far: There are several to choose from, but RB Nick Chubb is averaging 150 yards a game and has gone over 100 in 12 straight games.
Some teams bound to get beat:
When it could happen: This week against Ohio State.
Why: The defense has given up 499 yards a game against weak opposition.
Why they might keep winning: QB Nate Sudfeld maintains his 7-to-1 TD-to-interception ratio.
NORTH CAROLINA STATE
When it could happen: This week against Louisville.
Why: The record is built against overmatched competition. The Wolfpack were 4-0 at time this last year before going 3-5 in the ACC.
Why they might keep winning: The rushing game keeps generating 250 yards a game and the defense holds steady.
Star, so far: Matt Dayes has run for 100-plus yards in all four games.
When it could happen: Oct. 15 at Stanford.
Why: Bruins have to go to Utah in November, and as good as QB Josh Rosen has been, he's still a freshman, and he won't navigate the Pac-12 without throwing in a clunker somewhere.
Why the Bruins might keep winning: Rosen keeps growing and the defense is able to manage without Myles Jack.
Star, so far: Except for his struggles against BYU, Rosen has lived up to his five-star recruiting rating.
When it could happen: Oct. 17 at Michigan.
Why: The injury list seems to get longer by the week, and pass defense is a major concern.
Why the Spartans might keep winning: The Connor Cook-led offense keeps scoring 30-plus points a game.
Star, so far: WR Aaron Burbridge has more than twice as many catches (24) as the team's No. 2 receiver.
When it could happen: Nov. 7 at Oklahoma State.
Why: The defense isn't as good as expected, and it's playing in a conference whose calling card is high-scoring offenses.
Why the Horned Frogs might keep winning: QB Trevone Boykin and WR Josh Doctson keep putting up crazy numbers.
Star, so far: Doctson already has 35 catches, most of any receiver at a Power Five school, and he already has six TDs.