PITTSBURGH -- Ben Roethlisberger isn't the only Steelers quarterback who might be out for four weeks.
Byron Leftwich has a second-degree sprain of the medial collateral ligament in his left knee, sources told ESPN senior NFL analyst Chris Mortensen on Friday.
Mortensen was the first to report the injury.
Leftwich's injury could sideline him for most or all of the first month of the season, leaving the Steelers with only two healthy quarterbacks -- Dennis Dixon and Charlie Batch -- for their Sept. 12 opener against Atlanta.
Given how secretive coach Mike Tomlin was in refusing to announce a starter for any preseason game, it isn't certain when he'll disclose his starting quarterback. The Steelers don't practice again until Monday.
After the Steelers learned the nature of Leftwich's injury, Dixon was taken out of Thursday's game against Carolina after throwing a single pass, for a touchdown -- a strong indication he was being protected for the opener. Batch played the final 2½ quarters, throwing only four passes.
After working with four experienced quarterbacks during training camp, an awkward situation that resulted in Batch getting almost no work with the starters, the Steelers suddenly are down to two.
"Of course, I'll be excited if it does come my way," said Dixon, the third-year quarterback who got more preseason playing time with the starters than any quarterback except Roethlisberger. "At the same time, I'm even keel. I never get too high or never get too low."
An MRI exam performed Friday on Leftwich apparently did not reveal a torn anterior cruciate ligament, which could have sidelined him for the season. A strained medial collateral ligament is less serious, but still commonly takes weeks to heal. The team did not disclose any projected timetable on Friday.
This injury couldn't have occurred at a worse time for the Steelers, who traded for Leftwich in April with the intent of starting him while Roethlisberger served his suspension for violating the NFL's personal conduct policy. That punishment was reduced Friday to four games by NFL commissioner Roger Goodell, meaning Roethlisberger can return for the Oct. 17 home game against Cleveland.
Now, the Steelers must find a way to remain competitive until Roethlisberger gets back.
"I think we're in good hands," Batch said. "You had three solid guys who could step in when needed, and now we're down to two."
Batch, a Steelers backup since 2002, owns an extensive knowledge of the playbook and often huddles with Roethlisberger between series to review coverages. Batch also played well while Roethlisberger was injured in 2005 and 2006, going 3-0 as a starter.
However, Batch has thrown only two passes since the final game of the 2007 season. He missed the 2008 season with a broken collarbone that occurred in the first preseason game, then went down with a wrist injury shortly after entering the only game he played last season.
Dixon has started a single NFL game, throwing for a touchdown and running for another during a 20-17 overtime loss at Baltimore last season. The former Oregon star's running ability gives the offense an extra dimension, but Tomlin said Dixon still must learn when to stay with a play and when to take off running.
If Dixon starts, wide receiver Hines Ward predicts the Steelers will take a low-risk approach like they did when Roethlisberger became a starter as a rookie in 2004. Then, the Steelers leaned on their running game, defense and special teams while asking Roethlisberger to throw only enough to balance the offense.
Roethlisberger said there's no reason why the Steelers can't be as successful with Dixon as their starter as they were when he was forced to play after Tommy Maddox was injured in 2004. After the Atlanta opener, the Steelers play at Tennessee on Sept. 19 and Tampa Bay on Sept. 26 before meeting Baltimore at home on Oct. 3.
"It's going to be different for him whether it's on the road, at home, he's got nerves, jitters, he's going against a great nose tackle or a tough defense in Baltimore," Roethlisberger said. "It's going to be a challenge for him if he's indeed the starter, but I think he'll be up for it if his number is called."
The Steelers cut 10 players Friday and must make an additional 11 cuts Saturday to reach the 53-man roster limit.
Tight end Sean McHugh, who missed last season with a knee injury, was the most prominent player cut. Also let go were tight end Eugene Bright, guard Dorian Brooks, offensive tackle Kyle Jolly, wide receiver Brandon London, defensive tackle Scott Paxson, long snapper Matt Stewart, safety Justin Thornton, running back Justin Vincent and linebacker Renauld Williams.
Information from The Associated Press contributed to this report.