(Reuters) - The Pittsburgh Steelers were forced to rely on their defense to eke out a hard-fought 16-13 overtime victory over the Kansas City Chiefs on Monday after the home team lost talismanic quarterback Ben Roethlisberger through injury.

In a rain-soaked war of attrition in which Kansas City forced overtime with a late fourth-quarter drive, Pittsburgh ended the Chiefs' resistance soon after when a Lawrence Timmons interception set up Shaun Suisham's 23-yard winning field goal.

The Steelers (6-3) needed just 51 seconds of the extra session to seal a fourth straight victory that kept them one game behind the AFC North-leading Baltimore Ravens.

"We're a team, we're going to back each other up," Timmons told reporters. "We had each other's back, and we got the win."

Pittsburgh were expected to easily see off the struggling Chiefs (1-8) but the game did not follow the script and the home team battled to overcome a 10-0 deficit and a Roethlisberger shoulder injury that ended his game in the third quarter.

Roethlisberger tossed a first-half touchdown to Mike Wallace to tie the game at 10-10 at halftime but his duties were turned over to back-up Byron Leftwich after taking a big hit on the opening drive of the second half.

Roethlisberger left the stadium with his arm in a sling, and will undergo further tests with his team mates fearing he could miss future games.

"I asked him if he was alright. He didn't say anything, he just ran to the locker room," said Pittsburgh offensive lineman Maurkice Pouncey.

"Hopefully, everything pulls through. We need him."

STRONG START

The Chiefs surprised Pittsburgh early and completed a strong first-quarter drive with a 12-yard touchdown run from Jamaal Charles.

The 7-0 advantage was Kansas City's first lead of regulation this season as their only win came via an overtime triumph against New Orleans on September 23.

The Chiefs added a field goal for a 10-0 edge in the second after Steelers running back Isaac Redman lost a fumble.

Roethlisberger, however led his team back, getting a 35-yard field goal from Suisham before he connected with Wallace to tie it at 10-10.

The Steelers edged 13-10 ahead early in the fourth quarter before Kansas City rallied on their final drive to set up Ryan Succop's game-tying 46-yard field goal.

Kansas City could not celebrate long as quarterback Matt Cassel made a poor throw that found Timmons and extended the Chiefs' troubles with their sixth successive defeat.

The play was Kansas City's only turnover of the game even though they lead the NFL in the category.

Charles finished with 100 yards rushing, but Cassel completed just 11 of 26 passes for the Chiefs.

Roethlisberger had just 84 yards passing while Leftwich had 73.

"I believe that's why they have me here," Leftwich said.

"If something ever happens to Ben, we don't have to change anything we just go out there and play.

"I have to make sure I'm ready if he can't go."