TULSA, Okla. (AP) _ Oklahoma football coach Bob Stoops says offensive lineman Brian Simmons has injured his knee during a conditioning workout.
Stoops says doctors are still determining the extent of the injury.
Meanwhile, Stoops says freshman center Chad Roark has been granted a release from his letter of intent.
Roark graduated from Ada High School a semester early to take part in spring drills, but left the team late in the spring.
Roark's father says no decision has been made on where he'll transfer. His brother Chad plays at Nebraska.