KANSAS CITY, Mo. -- When the last player drafted in 2009 trotted onto the field, the best team of 2008 was doomed.

A few minutes after Ben Roethlisberger wobbled off the field Sunday with a possible concussion, Ryan Succop kicked a 22-yard field goal with 8:28 left in overtime and the Kansas City Chiefs snapped a team-record 10-game home losing streak with a 27-24 victory over the stunned Pittsburgh Steelers.

Chris Chambers' 61-yard catch-and-run set up Succop, and "Mr. Irrelevant" booted through the game winner for the Chiefs (3-7), whose stadium was crammed with tens of thousands of towel-waving fans of the Steelers (6-4).

Roethlisberger had thrown for 398 yards and three touchdowns when he apparently took a knee to the helmet while being sacked by Derrick Johnson and gave way to Charlie Batch. Coach Mike Tomlin said he was not certain how severe the injury might be.

"He took a blow, needless to say, it was a concussion-oriented thing so I doubt he was going to come back into the football game," Tomlin said. "I don't have a lot of information in terms of where he is or his level of availability. We will have more information as we proceed."

Just before Chambers' big play, Steelers cornerback Ike Taylor dropped a possible interception.

"This job is not for the faint of heart," said a beaming Todd Haley, the Chiefs' rookie coach.

Matt Cassel had a horrendous first half, passing for only 35 yards on four completions. But he came through in the final two quarters and overtime, finishing with 248 yards and two touchdowns.

"I've got to hand it to [Cassel], the kid's a fighter," said Haley, who grew up accompanying his father to Steelers training camp, where the elder Haley worked as a personnel executive. Haley lost to Pittsburgh in last year's Super Bowl when he was Arizona's offensive coordinator.

"It's nice to get a little reward against a team like that. I thought the guys really showed heart and guts," he said.

The Chiefs faced third down when Cassel connected with Chambers, who was signed three weeks ago off waivers from San Diego. He went 61 yards before he was pushed out of bounds at the 4.

Succop, the final player drafted in April, came in and clinched the Chiefs' first home victory in more than a year. Succop also had a 27-yarder that tied it 17-all in the final seconds of the third quarter.

It was the second loss in a row for the Steelers, who have fallen twice to division rival Cincinnati and were without injured Pro Bowl safety Troy Polamalu. Defensive end Chris Kemoeatu also went out with a knee injury.

In regulation, the Steelers (6-4) had the ball for almost 19 minutes longer than the Chiefs (3-7) and outgained them 463-206. The Chiefs stayed in it with Jamaal Charles' 97-yard return of the opening kickoff and Andy Studebaker's 94-yard return of an interception.

"I think we lost the momentum in the third quarter with all the turnovers and stuff like that," said Steelers wide receiver Hines Ward, who had 10 catches for 128 yards, including an 8-yard touchdown. "When you let a team hang around like that, you give them a chance. When you give them hope, they thrive off the crowd noise. They took it into overtime and did what they had to do."

Studebaker, making his first NFL start, picked off Roethlisberger's pass 2 yards deep in the end zone in the third quarter and motored to the Steelers 8 before running back Rashard Mendenhall dragged him down.

"Once I picked it off, 100 yards looked like a long way," he said. "It was a fun play."

But Cassel was sacked twice in the next three plays, and the Chiefs had to settle for Succop's 27-yarder.

Roethlisberger's 8-yard touchdown pass to Mendenhall gave the Steelers a 24-17 lead a few minutes later after the Steelers recovered Cassel's turnover at the 27.

But back came KC, playing without suspended wide receiver Dwayne Bowe. Cassel hit Lance Long for 30 yards and Chambers for 47 to set up a 2-yard TD pass to Charles that tied it 24-all with a little under 5 minutes left.

Cassel also had a 21-yard TD pass to Leonard Pope early in the third quarter.

Charles, who got the Chiefs' first rushing touchdown of the year the week before, got their first kickoff return for a TD in four years. He took the opening kickoff at the 3, started left and then veered right and was hardly touched. It was the fourth time in five games Pittsburgh yielded a kickoff return for a touchdown.

It was the Chiefs' first home win, and first win over an opponent with a winning record, since they beat Denver in the fourth week of the 2008 season. It was the first time they'd posted back-to-back wins since Oct. 14-21, 2007.

"To do it against the defending Super Bowl champions is a great feeling," said Succop. "A lot of hard work has gone into it and our coaches and players and everybody has really bought in."