PITTSBURGH – Their franchise quarterback on his way to the hospital, the momentum firmly on the other side of the field after a stunning last-minute rally by one the NFL's worst teams, the Pittsburgh Steelers appeared lost.

Then linebacker Lawrence Timmons provided a reminder that – Ben Roethlisberger or no Ben Roethlisberger – Pittsburgh's identity begins and ends with defense.

Timmons intercepted Kansas City quarterback Matt Cassel on the second snap of overtime, and Shaun Suisham drilled a 23-yard field goal one play later to lift the Steelers to a 16-13 victory over the hapless Chiefs.

"We just stayed positive," Timmons said. "It's easy to get down on yourself, but we are not like that. We stand up, face adversity."

Good thing, because there's plenty to go around.

The Steelers (6-3) have won four straight but played most of the second half without Roethlisberger, who left with a right shoulder injury in the third quarter after getting sacked by Kansas City linebackers Tamba Hali and Justin Houston.

Coach Mike Tomlin wouldn't speculate on the severity of Roethlisberger's injury, and his status for Sunday's showdown with AFC North leader Baltimore is uncertain.

Veteran backup Byron Leftwich completed 7 of 14 passes for 73 yards in his first regular-season game in nearly two years.

"It wasn't a pretty body of work by any of us, but his consistency remains the same in terms of being a stabilizing force for us," Tomlin said of Leftwich.

Jamaal Charles ran for 100 yards and a score for the Chiefs (1-8), who have lost six straight.

The Chiefs had their chances, taking their first lead in regulation all season in the first half, then overcoming a series of embarrassing miscues to tie the score 13-13 at the end of regulation.

Taking over at the Kansas City 20 with 1:51 remaining, Cassel led the Chiefs 52 yards – converting a fourth-and-15 in the process – to set up a 46-yard field goal by Ryan Succop as time expired.

"We went up against a good football team, and unfortunately we weren't able to pull it out in the end," Cassel said, "but I thought the way the guys handled the environment of 'Monday Night Football' was great."

Kansas City's only win this season came in overtime at New Orleans in September. Any chance at a repeat faded when Cassel's pass on the second play of extra period landed in the hands of Timmons, who returned it 23 yards.

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