The Westgate SuperBook in Las Vegas had Alabama as a seven-point favorite Saturday night, moments before Clemson shut out Ohio State 31-0 in a College Football Playoff semifinal in the PlayStation Fiesta Bowl.
Earlier Saturday, the undefeated Crimson Tide advanced to their second straight title game with a 24-7 win over Washington in the Chick-fil-A Peach Bowl.
By Sunday, the line had dropped down to Alabama minus-6.5 at most sportsbooks.
Alabama beat Clemson 45-40 as a 6.5-point favorite in last year's national championship game.
The Tigers have won five of their six bowls as underdogs, including the impressive blowout of Ohio State on Saturday. Clemson was as much as a 3.5-point underdog to the Buckeyes in December, but money flowed in on the Tigers leading up to kickoff, shrinking the line to Ohio State minus-1 at some sportsbooks.
Heading into the championship game, Alabama has been favored in 96 of its past 97 games. The Crimson Tide were consensus one-point underdogs at Georgia on Oct. 3, 2015. They won that game 38-10.
The over/under for the national championship game opened at 54.5.