Source: Taj Gibson has MCL sprain

CHICAGO -- An MRI on Taj Gibson's left knee revealed a sprained MCL on Monday, according to a league source. The timetable on his return to the Chicago Bulls' lineup is uncertain.

The veteran forward injured his knee in the second half of Sunday night's loss to the Oklahoma City Thunder and spent some extra time in the training room having it checked out.

Gibson, who signed an extension on opening night this season worth upwards of $38 million has struggled to find a rhythm at times this year, but has played better of late. He is averaging 7.7 points, 5.4 rebounds and 1.4 blocks a game.

His injury will put even more pressure on Carlos Boozer to succeed and produce on both ends of the floor.

The Chicago Tribune earlier reported Gibson's MRI results.