The Carolina Panthers will have to face Tony Romo and the Dallas Cowboys without their franchise leader in interceptions and the second-leading tackler in team history.

Starting cornerback Chris Gamble is listed as out for Sunday’s game against Dallas with a shoulder injury that could cost him the rest of the season.

Coach Ron Rivera also said starting middle linebacker Jon Beason is “very doubtful” to play against the Cowboys.

Gamble was injured against Atlanta in Week 4 and sat out the following Sunday against Seattle. The Panthers gave him two weeks of rest, and he participated fully in practice on Wednesday.

But when he jammed a receiver at the line during drills, his shoulder was reinjured.

“The week off was great until he took a shot, and it’s been downhill ever since,” said Rivera, who added there’s a possibility that Gamble may have to be put on injured reserve.

Gamble will get an MRI on his shoulder this weekend, and the Panthers could know whether a move to IR is imminent before the game. Rivera said he fears the injury is similar to the torn labrum reserve guard Mike Pollak suffered earlier in the season that placed him on IR.

A ninth-year player, Gamble was the second-most effective defensive back in 2011 according to ProFootballFocus.com. He allowed one reception for every 18.1 snaps, which was second to only Philadelphia’s Nnamdi Asomugha.

Captain Munnerlyn will start opposite rookie Josh Norman and will slide to nickel in certain packages, with Josh Thomas playing cornerback.

For Beason, the three-time Pro Bowler missed his third-straight practice with a knee injury. Rivera said Beason had been taking as many “mental reps” as possible on the field, but that he was still “very, very limited” during practice.

Should Beason be unable to go Sunday, rookie Luke Kuechly will take over at middle linebacker for the second straight game. Kuechly had 11 tackles and one interception against the Seahawks in Week 5.

Rivera said the linebacking corps will be the same against the Cowboys, with Kuechly at middle, James Anderson at strongside and Thomas Davis at weakside.

“(Kuechly) has handled (MLB) very well,” Rivera said. “And James Anderson has really been an outstanding pro. He helps. It doesn’t matter who the Mike linebacker is, when you have a guy like James Anderson who gets it, that helps. It takes a lot of pressure off others.”

Learning to finish: Earlier this week, injured center Ryan Kalil noted the Panthers are 2 yards away from being a 3-2 team.

Had the Panthers been able to score a touchdown on fourth-and-goal from the 1 against Seattle, or get a first down against Atlanta in the closing minutes, Carolina’s record would be much different than it is now.

It’s difficult to simulate finishing games in practice, so the coaching staff emphasizes finishing plays, hoping that will carry over to Sundays.

“As the play’s winding down, the stress is to finish it,” Rivera said. “Running backs take it past a certain point. Defensive players get after the ball and get all 11 guys around the ball. Offensive line, hey the ball’s thrown we’re breaking downfield to cover. Those are all those little emphases that you can have.”

3-4 scheme: For the first time all season, the Panthers will face a consistent 3-4 defense Sunday.

The team had seen flashes of it against Seattle and Atlanta, but the Cowboys are the first team the Panthers have faced who employ the scheme on a regular basis since the preseason.

Leading the way is outside linebacker DeMarcus Ware, who is tied for third in the NFC with six sacks and tied for first in the conference in forced fumbles with three.

“A guy like him is very vital to what you do in a 3-4,” Rivera said. “Whether you line up outside linebacker or move him around as a rush in, a lot of your front can be designed around a guy like that. And if you hit it just right, as an offense, you got a chance for a big play. But if you don’t, he’s got an opportunity for a big play, and he’s got the skill set.”

Flags not flying: The Panthers’ offense is the second-least penalized offensive unit in the NFL, with just 25 through five games. The defense is the second-least penalized defensive unit, with 20.

Rivera attributed that to the team’s discipline in practice.

“We’re working on the discipline of not jumping,” Rivera said. “This year a lot of it has been our technique, we’ve gotten better at it. Guys understand more of what we’re trying to do. We’ve talked about the discipline of staying onside because that was one of our big issues last year.

“As far as the holding being down, I think that has to do with the guys working their techniques and being more comfortable in the scheme offensively and defensively.”