2025 NFL playoffs, odds, betting: San Francisco 49ers are biggest playoff underdogs in over 40 years against Seahawks

The San Francisco 49ers pulled off an improbable 23-19 win at the Philadelphia Eagles as sizable 5.5-point underdogs on Sunday to reach the divisional round. The 49ers overcame two interceptions from Brock Purdy to win on the road against the Super Bowl champions.

Brock Purdy & Co. will face a familiar foe on Saturday, as the 49ers will travel to Seattle to play their NFC-West division rivals for the third time this season.

If San Francisco wins, it will be a historic upset, according to oddsmakers.

The 49ers are currently 7.5-point underdogs at the No. 1-seeded Seahawks at BetMGM. If the line holds, it would mark the biggest underdog that San Francisco has been in the postseason in over 40 years.

The 49ers were 10-point underdogs at Washington all the way back on Jan. 8, 1984, a game in which they lost 24-21 (but did cover the spread). San Francisco was also a 7-point 'dog back on Dec. 27, 1970 against the Minnesota Vikings; the 49ers won outright 17-14.

San Francisco split the season series with the Seahawks, but lost 13-3 to Seattle in Week 18 to fall to the No. 6 seed and give Seattle the top seed in the NFC and the accompanying bye. The 49ers have only scored 20 total points in two games against the Seahawks' ferocious defense.

In addition to losing Nick Bosa, Fred Warner, Mykel Williams and Trent Berthune for the season prior to the Eagles game (along with wideout Ricky Pearsall being inactive), the 49ers lost star tight end George Kittle to a torn Achilles during the game.

Pearsall could be back for Saturday's game, but it will no doubt be a shorthanded San Francisco team heading into one of the toughest venues to play in the NFL against a well-rested Seahawks squad.

Underdogs went 4-2 against the spread in the wild-card round.