Philadelphia Eagles are first No. 1 seed ever to open as underdog vs. Atlanta Falcons

The Philadelphia Eagles are the first No. 1 seed in the NFL playoffs to begin as an underdog.

The Atlanta Falcons opened as 2.5-point favorites over the Eagles in Saturday's divisional round game in Philadelphia.

Since 1975, when the NFL began basing home-field advantage on teams' regular-season winning percentage, no No. 1 seed has ever been an underdog in its first playoff game, according to ESPN Stats & Information. The line can change by Saturday.

The reason for the Eagles being the underdog likely relates to quarterback Carson Wentz suffering a season-ending knee injury in early December. Backup Nick Foles has not produced at the same rate as Wentz under center.

According to ESPN, Westgate Superbook oddsmaker Ed Salmons estimates the Eagles, with a healthy Wentz, could have been as much as 6.5-point favorites over the Falcons. Without him, Salmons and other Las Vegas oddsmakers say Philadelphia would be an underdog to any other team in the NFC playoffs this week.

The Falcons beat the Los Angeles Rams 26-13 Saturday to advance. They will play at Philadelphia as the first No. 6 seed to be favored in the divisional round.

Bettors were siding with the Falcons over the Eagles early. The line had already grown to Atlanta minus-3 on Sunday morning at some sportsbooks.