Dabo Swinney commends Justin Fields and Ohio State on their talent and expresses his excitement about facing them. (1:18)

Swinney: This is the most complete Ohio State team we've played (1:18)

The undefeated Big Ten champion Ohio State Buckeyes are underdogs heading into the College Football Playoff.

No. 3 Clemson opened as a 2-point favorite over No. 2 Ohio State on Sunday at Caesars Sportsbook. The Tigers and Buckeyes will face off Dec. 28 in the Fiesta Bowl in the second semifinal.

No. 1 LSU opened as a 10-point favorite over No. 4 Oklahoma in the other semifinal. LSU and the Sooners play Dec. 28 in the Chick-fil-A Peach Bowl.

Ohio State went from a potential double-digit favorite over Oklahoma to an underdog with the CFP selection committee's decision to move LSU past the Buckeyes and into the No. 1 seed. Caesars Sportsbook oddsmakers were considering making Ohio State an 11.5-point favorite over Oklahoma. Instead, the Buckeyes are underdogs for the first time this season.

The favored team has won nine of 15 CFP games.

LSU is the fifth double-digit favorite in College Football Playoff history. The previous four won straight-up, and double-digit favorites overall have won their games outright 89.6% of the time over the past five seasons, according to ESPN Stats & Information.

The point spreads for both semifinals were on the move quickly Sunday afternoon. An hour after sportsbooks posted their opening lines, the consensus lines were Clemson -2.5 and LSU -11.5.

LSU, at 3-2, has the best odds to win the national championship at Caesars Sportsbook, followed by Clemson (2-1) and Ohio State (5-2). Oklahoma is a 12-1 long shot.

Clemson is the seventh lower seed to be favored in a CFP game. Lower-seeded favorites are 4-2 in the CFP.

The over/under on Clemson-Ohio State opened at 63.5 at Caesars Sportsbook. The over/under on Oklahoma-LSU opened at 75.5.