Duke's Mike Krzyzewski undergoes successful back surgery

Duke coach Mike Krzyzewski underwent successful lower back surgery on Friday, the school announced.

The procedure was performed to remove a fragment of a herniated disk. Krzyzewski is expected to miss four weeks.

Duke University Hospital surgeon Dr. Allan Friedman performed the surgery.

"Surgery went exactly as planned," Friedman said in a statement. "Coach is in terrific physical shape and we expect a full recovery."

Jeff Capel will serve as the acting head coach while Krzyzewski recovers. The Blue Devils host Boston College on Saturday.