– Big Ben was the only postgame topic that really mattered to the Pittsburgh Steelers. Michael Vick's reaction when Ben Roethlisberger went down in the third quarter, and he had to grab his helmet and go, said it all.

"I was kind of stunned," the Steelers backup quarterback said after finishing a 12-6 victory over the St. Louis Rams on Sunday. "You never want to see a guy like Ben go down."

The Steelers scheduled a magnetic resonance imaging exam for Monday and Roethlisberger's left knee injury will be re-evaluated after that but coach Mike Tomlin had no other updates beyond saying, "Ben's got a knee."

Vick completed five of six passes for 38 yards in relief, and he won't have much time to prepare for the Steelers' next game if he has to play: Pittsburgh (2-1) plays host to Baltimore (0-3) on Thursday night.

Running back Le'Veon Bell scored from a yard out in the first half in his first game back after a suspension, but the Steelers needed their defense to step up without a quarterback who has been hard to knock out.

"You grow infinitely when you pull those out," Tomlin said. "Obviously not the type of game we're searching for, but a win nonetheless."

The Rams were 2-for-10 on third down and 0-for-2 on fourth down and limited to 258 yards. Will Allen's interception with 1:56 left set up a field goal by Josh Scobee to put Pittsburgh ahead by six points.

"Fourth-quarter picks are great," Allen said. "Lawrence Timmons did a great job of causing a hot throw and I was just in position."

Pittsburgh averaged 32 points in its first two games but was held down well before Roethlisberger's leg got caught underneath him on a diving, sliding sack by Mark Barron. The two-time Super Bowl-winning quarterback had to be carted off.

Tomlin had no problem with the play.

"I just caught his leg on the way in," Barron said. "I didn't have nothing to do with his knee, I didn't see how he fell."

The Rams (1-2) were held to two field goals and have scored only 16 points over the past two games. Their last chance ended when a potential first-down catch by Kenny Britt near midfield with 1:19 to play was overturned by officials.

"I thought I had the ball coming down, I threw it back to the ref after I landed," Britt said. "I made the catch and they decided if it's a catch or not."

Roethlisberger hasn't missed a game since late in 2012. He won his franchise-record 108th game, passing Hall of Famer Terry Bradshaw, while completing 20 of 24 passes for 192 yards and an interception.

"We'll be saying those prayers for Big Ben," Rams quarterback Nick Foles said.