Adam Vinatieri added a 44-yard field goal early in the second quarter — pairing it with a 25-yarder in the first quarter — and the Colts led 13-6. From there, it was all downhill for the home team.
Buffalo tied the game on a 107-yard kickoff return by rookie Marquise Goodwin and took the lead when rookie E.J. Manuel threw a 17-yard touchdown pass to tight end Dorin Dickerson to cap a 10-play, 92-yard drive just before the end of the first half.
Tuel added to the lead with the first of his scoring passes — a 6-yarder to rookie Da'Rick Rogers on the first series of the third quarter — and threw a 5-yard touchdown to wide receiver Brandon Kaufman in the fourth quarter.
Buffalo also got 24- and 23-yard field goals from Dustin Hopkins in the first half and a 30-yarder by Rian Lindell in the second. The Bills capped the scoring with a 17-yard interception return by Jumal Rolle with 5:01 remaining.
Indianapolis' only score of the second half came on a 72-yard fumble return by rookie cornerback Daxton Swanson. The play was set up by a sack from linebacker Caesar Rayford that caused Tuel to fumble, one of two turnovers forced by the Colts' defense Sunday.
The Colts had 17 players on the inactive list, including defensive starters Jerrell Freeman, LaRon Landry and Pat Angerer and rookie outside linebacker Bjoern Werner. Four more players left the game with injuries — linebacker Justin Hickman, cornerback Cassius Vaughn, rookie defensive tackle Montori Hughes and linebacker Quinton Spears.
Second-year tight end Dwayne Allen did not play after injuring his foot during a training camp practice Tuesday night at Anderson University. Pagano said he likely will miss a few weeks, but the team hopes to have him ready for the regular-season opener Sept. 8 against the Oakland Raiders.