LAKE FOREST, Ill. – Depending on the availability of two injured players, the Bears could start their fifth different combination of linebackers in six games Sunday when they visit the Cincinnati Bengals.

Pisa Tinoisamoa underwent an MRI exam Monday after reinjuring his right knee in Sunday night’s loss to the Falcons. The strongside linebacker was carted to the locker room after hurting the same knee he had sprained on the first defensive play of the season, an injury that sidelined him for three games.

Pisa Tinoisamoa reinjured his right knee in the Bears' 21-14 loss to the Falcons Sunday night.

Jamar Williams filled in for Tinoisamoa Sunday night. But if a long-term replacement is needed, the Bears could turn to Hunter Hillenmeyer, who appears close to returning to action after missing the last two contests with a rib injury he sustained Sept. 27 in a win at Seattle.

The Bears could also move Nick Roach from middle linebacker to the strongside position and plug Hillenmeyer back in the middle, which is how they lined up in back-to-back games against the Steelers and Seahawks.

“All of those are options for us that we’ll look at,” said coach Lovie Smith. “Getting [Hillenmeyer] back on the football field is the first thing. Then we’ll put him back into the mix. The last time he was healthy he was playing for us. I can see him playing for us again.”

Despite the latest injury to Tinoisamoa, the Bears aren’t expected to sign another linebacker. They’ve already added reserves Tim Shaw and Darrell McClover at the position to bolster their special teams.

“I feel pretty good about the bodies that we have out there right now,” Smith said. “Whenever you have a player like Pisa go down, hopefully we can get Hunter to fill back in. Our numbers are still pretty good.”

Getting better: Second-year pro Marcus Harrison made his first NFL start at nose tackle Sunday night against the Falcons, registering two tackles and one tackle-for-loss.

Harrison teamed with Tommie Harris to drop Falcons running back Michael Turner for a three-yard loss in the first quarter. The 6-3, 312-pounder started in place of Anthony Adams, who has been bothered by a toe injury.

“[Harrison] did some good things,” Smith said. “He did some good things first off in practice last week. That’s why we started him. Anthony was a little banged up last week.

“Marcus is a good football player. He’s getting a little bit better every time we play. I thought he did some good things. We still need for him to take another step. He’s capable of that. He’s a big man and has a lot of athletic ability.”

Not injured: Matt Forte tweaked his knee in the Bears’ Week 3 win at Seattle. But one day after he was limited to 23 yards on 15 carries in Atlanta, Smith insisted that the running back is not bothered by an injury.

“Forte finished the game strong,” Smith said. “I wouldn’t say [he’s hurt]. He’s not on the injury list. He’s good to go. He didn’t have a lot of production [Sunday] night the way a lot of us didn’t. I don’t think [it’s] any more than that.”

In the Bears’ previous game—a 48-24 win over the Lions on Oct. 4—Forte rushed for a season-high 121 yards on just 12 carries, including a career-long 61-yard touchdown and a 37-yard run.

“The week before we weren’t talking about any of these things,” Smith said. “Matt will be fine just like the rest of our team.”

Enough Ced: Smith will see a familiar face Sunday in Cincinnati. But trying to contain former Bears running back Cedric Benson won’t be the coach’s only concern. Benson ranks second in the NFL in rushing with 531 yards and 4 touchdowns on 127 carries.

“I’m happy to see what Cedric is doing for the Bengals,” Smith said. “He’s having an outstanding season. We’re playing the Cincinnati Bengals now. That’s enough to keep us occupied. They have a lot of other good players that we’ll have to contend with.

“I know they’re not feeling good about a tough loss [Sunday to the Texans] like we are, but we’re anxious to get back on the practice field and to play them and get this taste out of our mouths.”

Roster move: The Bears again shuffled their practice squad Tuesday, re-signing center Donovan Raiola and terminating the contract of defensive end Ervin Baldwin, a 2008 seventh-round draft pick.