Ben Roethlisberger suffered a sprained MCL in his left knee and is expected to miss four to six weeks.

The Pittsburgh Steelers were relieved Roethlisberger didn't tear his ACL.

Besides the MCL sprain, Roethlisberger also suffered a bone bruise, according to the source.

"Ben is a competitor and we are confident he will do everything in his power to return at the appropriate time," Mike Tomlin said Monday in the statement.