Andrew Luck threw two touchdown passes and Adam Vinatieri made a tie-breaking 55-yard field goal with 6:13 to play, giving Indianapolis a surprising 27-24 victory over Denver.
The Colts (4-5) ended a three-game losing streak and stayed atop the AFC South by ruining Peyton Manning's return to Indy again.
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Denver (7-1) was the only unbeaten team to lose this weekend.
Luck was brilliant, going 21 of 36 for 252 yards. He broke a 17-17 tie with a TD pass early in the fourth quarter, then helped snap a 24-24 tie by setting up Vinatieri for the field goal on the next drive. Indy ran out the final 5:57.
Manning was 21 of 36 for 281 yards with two TDs and two interceptions. He couldn't break Brett Favre's record for regular-season wins (186) by a quarterback and fell 3 yards short of becoming the NFL's career passing leader.