Bradley Roby returned Jamaal Charles' second fumble 21 yards for a touchdown with 27 seconds left Thursday night, completing a stunning comeback for a 31-24 victory over the Chiefs.
Manning threw for 256 yards and three scores, the last to Emmanuel Sanders with 36 seconds left as the Broncos (2-0) appeared to force overtime. But on the next play by the Chiefs (1-1), Charles was stripped by Brandon Marshall and the ball bounced right into Roby's hands.
"I'm not quite sure I'd ever been in one quite like that," Manning said.
The dramatic about-face came after Knile Davis gave Kansas City the lead with 2:27 left on an 8-yard run, raising hope among a sellout crowd that the Chiefs might finally end some curses.
Instead, Denver pushed its winning streak to seven straight over its AFC West rival, while the ageless Manning quieted his many doubters by improving to 14-1 in his career against the Chiefs.
Charles finished with 125 yards rushing and a touchdown, but he will only remember his fumbles — one in the red zone early in the game, the other deep in his own territory late in the game.
Alex Smith threw for 191 yards for Kansas City, but he also was picked off twice.
Manning threw a pick-six of his own, but he responded when it mattered the most.
The Broncos had taken over at their own 20-yard line with 2:27 left and trailing 24-17, and the seven-time All-Pro marched them calmly down field. He found Demaryius Thomas for three long receptions to get deep into Chiefs territory, then hit Sanders over the middle on third-and-10 from the Chiefs 19 for the tying touchdown that kept the Broncos alive.
The late-game dramatics transpired after the Chiefs bolted to a 14-0 lead in their home-opener, energizing a boisterous crowd that had been tailgating all afternoon.
But like he has so often against the Chiefs, Manning answered by leading Denver on an 80-yard TD march late in the first half. The capper was a pass over the middle to Sanders, who slipped between the safeties and somersaulted into the end zone for the 16-yard catch.
After swapping field goals, the Chiefs appeared to put the game away when Davis took a handoff and raced into the end zone late in the fourth quarter.