The knee injury that sidelined Rashad Evans from UFC 170 is apparently more severe than first believed.

Initial reports indicated that Evans (21-3-1), who pulled out of his scheduled co-main event clash against Daniel Cormier late Wednesday night, would be out of action for four weeks.

However, on Thursday UFC President Dana White told reporters in Las Vegas that Evans' timetable is far more dire than expected, and the former light heavyweight champion will require surgery that will leave him "out for a while."

White was unsure regarding the specific nature of Evans' knee injury.

Evans' injury initially led to Cormier's removal from UFC 170's fight card, however Thursday morning UFC officials signed undefeated newcomer Patrick Cummins (4-0) to square off against Cormier (13-0) on less than two weeks notice.