Scott Brown of the Pittsburgh Tribune-Review reports that an MRI has confirmed that Pittsburgh Steelers quarterback Byron Leftwich has a torn MCL in his left knee.

The injury will sideline the Steelers' temporary starting quarterback indefinitely.

With Ben Roethlisberger suspended for at least the first four games of the 2010 season, Leftwich's injury leaves just Dennis Dixon and Charlie Batch as the healthy quarterbacks on the roster. This reality may prompt the Steelers to look outside the organization for depth at the position.