St. John's starting center Chris Obekpa will sit out an estimated 10 to 14 days with a right ankle injury suffered in practice Monday.

An MRI on Tuesday revealed a sprain and a bone bruise. Obekpa has been ruled out for Tuesday night's home game versus Butler and Saturday's clash with No. 9 Villanova in Philadelphia. He's also likely to miss the home game versus Xavier next Tuesday, according to St. John's.

"Chris is a central part of what we do on both ends of the court. Our team will have to step up collectively in his absence," St. John's coach Steve Lavin said in a statement released by the school. "One of our team's strengths is depth so we are confident in our front-line players' ability to see us through this challenging stretch."

The injury comes at a particularly bad time. After an 0-5 start in Big East play, St. John's (17-9, 7-6) has surged back into NCAA tournament at-large bid contention. The Red Storm have won five in a row and eight of their past nine, and on Monday entered ESPN bracketologist Joe Lunardi's projected NCAA tournament field for the first time since the preseason. But they are still very much on the bubble.

Obekpa has been a key to St. John's recent success. The 6-foot-9 sophomore emerged from a midseason funk to score in double figures in four of the team's past six games. He's also a game-changer on defense -- currently 11th in the nation in blocked shots with 3.2 per game.