Kansas City, Mo. — The curse of Peyton Manning and the Denver Broncos lives on in Kansas City.

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. “That was a new one for me.”

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 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, red-clad 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 touchdown reception.

Two plays later, Aqib Talib picked off Smith on a poorly thrown play in the flat, and the Broncos needed just four plays for Manning to find Virgil Green with the tying touchdown toss.

After swapping field goals, the Chiefs appeared to put the game away when Davis took a handoff from Smith as the quarterback fell down and raced into the end zone late in the fourth quarter.

Turned out to be not late enough for Manning and the Broncos.

QB McCown expected to get start for Browns

Josh McCown slid a little closer to starting the Browns’ home opener.

Still making progress after sustaining a concussion while trying to dive into the end zone for a touchdown against the Jets last week, McCown is expected to be cleared to practice today. As long as he gets medical clearance and gets on the field, coach Mike Pettine indicated he will play his starting quarterback over Johnny Manziel on Sunday against Tennessee.

“We’ve discussed it, and I think it still will be our decision based on how practice goes,” Pettine said Thursday. “But I don’t see an issue if he’s cleared and practices fully tomorrow, barring anything unforeseen, a reason why we wouldn’t play him.”

Extra points

The Patriots acquired WR Keshawn Martin from the Texans for an undisclosed draft pick.

... QB Ryan Mallett will start for the Texans on Sunday at Carolina, coach Bill O’Brien said.

O’Brien had said earlier in the week that he wouldn’t announce a decision until game time. But after the news got out on Wednesday, O’Brien decided to make it official on Thursday.

Brian Hoyer (Michigan State) beat out the former Michigan quarterback for the job in camp. But Hoyer was benched in the fourth quarter of the Texans’ season-opening loss to the Chiefs after committing two turnovers. Mallett led Houston on two scoring drives in the final six minutes of the 27-20 loss.

... New photos show the severity of the injury to Giants DE Jason Pierre-Paul’s right hand, clearly showing his index finger mostly missing and his thumb and middle finger also damaged. He remains unsigned and is not being paid.

... Two-time Pro Bowl WR Julio Jones (sore hamstring) missed practice for a second straight day but promised to be in the starting lineup for the Falcons Sunday.