John Fox has some bad news for the other 31 NFL teams: Peyton Manning could be even better in 2013.

The Denver Broncos coach said Thursday at the league's annual scouting combine that with another off-season to heal and to fine-tune his comfort with Denver's offense, the four-time MVP and reigning Comeback Player of the Year could have a more impressive second season in the Mile High City.

Fox says a year ago the Broncos were doing homework on Manning. They saw a dramatic improvement in Manning's workouts last off-season at Duke, and then with the quarterback's passing in the second half of the 2012 season.

Manning led Denver to the AFC's best record, 13-3.  (AP)