Two from the Big Ten. Two from the Southeastern Conference. And the undefeated defending national champions on the outside looking in — for now.

Ohio State, LSU, Alabama and Penn State were the top four teams Tuesday night in the College Football Playoff selection committee's first rankings of the season.

Next up was Clemson, winner of two of the last three playoffs, followed by Georgia and Oregon. The 13-member committee will produce four more weekly top 25s before the only ones that really count come out on selection Sunday, Dec. 8.

The semifinals will be held this season at the Fiesta Bowl in Glendale, Arizona, and the Peach Bowl in Atlanta on Dec. 28. The national championship game is Jan. 13 in New Orleans.

The top four in the selection committee's initial rankings have never all reached the semifinals in the playoff's five-year history. Eleven of the 20 teams that started in the top four of the CFP rankings have reached the playoff, but, oddly, never the team ranked third.

Utah was eighth and Oklahoma, the highest-ranked team from the Big 12, was ninth. Florida gave the SEC four of the top 10 teams.

Another SEC team, Auburn, was 11th, followed by Baylor, one of the country's surprising unbeaten teams.

The highest-ranked team among Group of Five conference schools was Cincinnati out of the American Athletic Conference at No. 20. The top team from outside the Power Five conferences gets a New Year's Six bowl bid.

It was hard to call anything a surprise — or all that important — in the first rankings, but Clemson being out of the top four was notable.

"When you look at Penn State's résumé, with wins over (No. 15) Michigan and (No. 18) Iowa, those are marquee wins," said committee chairman Rob Mullens, who is also Oregon's athletic director. "Now, Clemson's coming on and playing its best football, but after Week 10, the committee thought (the Nittany Lions) were a notch above (Clemson)."

The good news for the Tigers is the teams in front of them have to play one another. LSU is at Alabama on Saturday. The teams are No. 1 and No. 2, respectively, in the AP Top 25 but are second and third in the CFP rankings.

Ohio State and Penn State face off on Nov. 23. The Nittany Lions also face a challenge this week when they visit unbeaten Minnesota, which was ranked 17th by the committee.

As long as Clemson keeps winning, the Tigers should be OK.

What could really turn the race inside out are upsets. With four weeks left before championship weekend when the playoff and bowl game berths are set, unranked teams have opportunities to provide potential twists and turns:

WEEK 11

Iowa State at No. 9 Oklahoma. The Cyclones came into the season ranked and were considered maybe the third-best team in the Big 12. They have lost three times, but by a combined 10 points. If the Sooners were to take a second loss, suddenly Baylor becomes not just the best playoff hope for the Big 12, but maybe the only one.

WEEK 12

UCLA at No. 8 Utah. The Bruins have won three straight games after a terrible start and are still in control of their Pac-12 South championship hopes. The Utes have been dominant, but coach Chip Kelly could turn this into his first signature win at UCLA and ruin the Pac-12's hope of a Utah-Oregon title game matching 11-1 teams.

Penn State at Indiana. The Hoosiers are on their way to their best season in 15 years and they will face the Nittany Lions after Minnesota and before Ohio State.

WEEK 13

Texas A&M at Georgia. The Aggies have already faced Alabama and Clemson. The Bulldogs might be more at their level. Another loss would all but eliminate the Bulldogs and could complicate the SEC's hopes of landing two teams in the final four.

WEEK 14

Texas A&M at LSU. If LSU is No. 1, this would be the third top-ranked team the Aggies have faced this season. Another chance to derail the SEC's master plan.

Clemson at South Carolina. Clemson has won five straight in the rivalry and most have not been close. It's hard to find even a hint of upset potential on the Tigers' schedule, but a rivalry game on the road. Maybe? And one loss could be one too many for Clemson considering what the committee seems to think of the state of the rest of the ACC.