INDIANAPOLIS (AP) -- Peyton Manning didn't have a touchdown pass or throw for 300 yards, so along comes backup running back Mike Hart to rescue the Indianapolis Colts and hand the Kansas City Chiefs their first loss of the season.
With Manning missing receivers all day, Hart found an inside crease in the Chiefs defense, crashed through three players for 11 yards and the game's only touchdown with 4:02 left to give the Colts a 19-9 victory Sunday.
The result leaves the NFL without an undefeated team just five weeks into the season.
"It's moments like this that you don't get all the time and when they pop, you try to take advantage of it," Hart said. "It's fun."
The 5-foot-9 Hart got his chance when Joseph Addai went down midway through the third quarter with what appeared to be a right shoulder injury.
Hart carried 11 times for 50 yards, both career-highs.
"Mike did a great job," Manning said after going 26-of-44 for 244 yards and one interception. "He had an interesting week practice wise. He got injured during the week and didn't know quite what was going to happen. Next thing you know, he comes out and does a heck of a job for us. That's why you've got to have depth. Everybody's got to be ready at any time."
Indy (3-2) needed a victory to get back into a first-place tie in the AFC South and was facing the hottest team in football.
Kansas City (3-1), with four straight wins dating to last season, was the NFL's last unbeaten team and brought a defense that hadn't allowed more than 14 points in a game all season - until Hart's run.
With Manning having a rare off day, the Colts featured a more balanced attack. The problem was Indy had deactivated backup running back Donald Brown , and when Addai was hurt, the Colts had to turn to Hart.
The Chiefs thought they had done enough defensively to thwart Manning & Co. with an assortment of nickel and dime packages that had the quarterback out of sync and flustered.
On a normal day, that might have been good enough to beat the Colts.
But Kansas City didn't get into the end zone, and for the first time since 1970, the NFL has no 4-0 teams. Denver, Detroit and the Los Angeles Rams all went 3-0 in '70 before losing.
"We're a team trying to transition into becoming a good team. We're not there," coach Todd Haley said. "If we had won this game, I'd be saying the same thing. Good is much bigger than four games. Good is measured a little differently, but we are transitioning and we are making progress."
Jamaal Charles carried 16 times for 87 yards. Matt Cassel was 16-of-29 for 156 yards, and the Chiefs had to settle for three field goals, losing their chance at a miracle comeback when Ryan Succop missed a 51-yard attempt with 1:17 to go.
The difference: Kansas City's failed gambles and Hart.
Haley opened the game with an onside kick that didn't go the necessary 10 yards. Nine plays later, Adam Vinatieri hit a 20-yard field goal.
On the next series, Cassel threw for a first down on fourth-and-2 from the Indy 8. When the ball was incomplete, Manning marched the Colts into position for a 24-yard field goal that made it 6-0.
"Going back to 2000, teams that have opened with an onside kick have had a plus-60 percent win percentage whether they got it or not and we knew that we would have to steal a possession in this game a couple of different ways," Haley explained. "When they work, you're good, when they don't, you're not good."
Then it was essentially a stalemate.
Succop hit a 45-yard field goal with 2 seconds left in the first half to make it 6-3. Vinatieri opened the second half with a 47-yarder and Succop countered with field goals of 35 and 43 yards to tie the score at 9.
Vinatieri finally broke the tie with a 42-yarder with 14:40 left to give Indy a 12-9 lead, and then the Colts put the ball in Hart's hands - who sealed it with his big run.
"Once I got the ball, the o-line, they took care of the front seven," Hart said. "I had two safeties back there and I was on the 3 to 4 yard line and it was my job to get in from there."
Notes: Indy has now won 10 of the last 11 games in this series, dating to 1990. ... The Colts had led the AFC South for 113 of 136 weeks before this season, but Sunday marked the first time they've been atop the division in 2010. ... Backup tackle Barry Richardson started in place of injured right tackle Ryan O'Callaghan, so when Branden Albert hurt his left elbow in the first half, the Chiefs moved left guard Brian Waters to tackle. ... The Chiefs have given up zero points off turnovers this season.