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CHICAGO -- Rex Grossman dived into the end zone, then ran to the side and spiked the ball. He had something to celebrate and the Chicago Bears had reason to exhale.

Grossman came off the bench to replace injured quarterback Kyle Orton and scored the go-ahead touchdown with 5:36 left, helping the Bears rally from a 10-point deficit for a 27-23 victory over the winless Detroit Lions on Sunday.

"I always thought odds are I was going to play a little bit, so we'll see what happens," said Grossman, the former starter who lost his job in the preseason. "I never figured that I wouldnt play at all. Odds are that at least two quarterbacks play some -- especially here in Chicago."

Matt Forte had 126 yards rushing for the Bears, who lost Orton to a right ankle injury and safety Mike Brown to a calf problem late in the first half. They didn't lose the game, though.

They can thank Grossman and Forte, who ran for 40 of Chicago's 54 yards on the go-ahead drive. His 19-yard dash put the ball on the 1 and Jason McKie got it back there with a 5-yarder after an illegal procedure penalty, setting up Grossman's 1-yard plunge that put Chicago ahead 27-23.

"That was a fun play, I guess," Grossman said.

Did he feel any personal satisfaction?

"No. It was team satisfaction all the way," Grossman said.

A source close to Orton told ESPN's Michael Smith on Sunday that the quarterback will miss at least a month with a high ankle sprain.

The game was a big relief for the Bears, who moved ahead of Green Bay to take sole possession of the NFC North lead.

Lance Briggs forced and recovered a fumble by Detroit's Michael Gaines at the Chicago 44 with 2:17 left, but the Lions got the ball back and drove to the Chicago 32. The Bears (5-3) then broke up a pass intended for Calvin Johnson in the end zone on the final play, and Detroit's search for a win continued.

After building a 23-13 halftime lead, the Lions (0-8) were in good position for their first victory since they beat Kansas City on Dec. 23. Instead, they're now the lone winless team.

While Daunte Culpepper agreed to a contract with Detroit, Dan Orlovsky made a case to keep his job after a brutal start. He was 28-of-47 for 292 yards and two touchdowns but threw two interceptions. Brown picked him off on the opening drive, leading to a field goal by Robbie Gould, and he tripped while dropping back to pass on the next possession. That resulted in an 11-yard loss, but things got better from there even though Craig Steltz intercepted a pass intended for Johnson at the goal line early in the fourth quarter.

"I'm a confident player and I have a confidence with the guys I'm out there with," Orlovsky said. "I try to stay even keel. I wasn't too high, wasn't too low. I knew they were going to make a little run. They're a good football team, but in the end I didn't do enough."

Grossman was 9-of-19 passing for 58 yards in a shaky performance that drew boos from the crowd.

His 6-yard TD pass to Rashied Davis midway through the third quarter pulled Chicago to 23-20, but it was clear why the Bears gave the job to Orton.

Passes by Grossman got deflected, and he was picked off by Dewayne White after Steltz's interception.

Still, the Bears won despite some scary moments. Meanwhile, the Lions lost another close game after dropping the previous three by eight points or fewer.

Jason Hanson had just kicked a 52-yard field goal to extend Detroit's lead to 10 with 1:05 left in the first half when Brown, who has a long history of injuries, walked to the locker room with a calf problem. Orton was taken from the field on a cart moments later, following a rollout to his right. He got hit by Cory Redding, and White fell on Orton as he was hitting the turf.

Orton finished 8-of-14 passing for 108 yards. He also had a 5-yard touchdown run.

The Bears beat the Lions 34-7 at Ford Field last month, and it looked as though more of the same was in store as Chicago grabbed an early 10-0 lead. But the momentum shifted quickly, with Johnson's 17-yard touchdown catch giving Detroit a 13-10 edge early in the second quarter.

Chicago had starting cornerbacks Nathan Vasher (wrist) and Charles Tillman (shoulder) back from injuries but had trouble stopping the Lions in the first half. Then, the Bears shut them down.

"I think our gut was checked and we came through in the end," Tillman said.

Game notes

The Lions' 23 points through the first two quarters were a season high for one half. ... Brown's interception was his first since last year's opener at San Diego, when he tore an anterior-cruciate ligament. ... LT Chris Williams, the 14th pick in the draft, played on special teams after being out the first seven games with a back injury.

Information from The Associated Press was used in this report.