Taj Gibson is expected to miss at least two weeks with a sprained left knee, forcing the Chicago Bulls to play without one of their key reserves at a pivotal point in the season.

Gibson stepped on the foot of Oklahoma City guard Reggie Jackson in the fourth quarter of Sunday’s 102-72 loss to the Thunder and knew something wasn’t right almost immediately.

”The first thing I did was grab my knee,” he said. ”I was in shock because I felt great. I went up for a regular shot block and I came down and it just gave way.”

Gibson had an MRI and was diagnosed with a sprained medial collateral ligament. He said doctors are planning to take another look to make sure there are no small tears.

– Reported by the Associated Press