Colts starting running back Vick Ballard will miss the rest of the season with a torn anterior cruciate ligament in his right knee.
Coach Chuck Pagano said Friday that Ballard was hurt making a cut in practice Thursday.
"It was a non-contact injury, just put a foot in the ground, went to cut on a running play and knee went out on him," Pagano said. "He'll require season-ending surgery, unfortunately. We feel awful for Vick."
Former New York Giants star Ahmad Bradshaw is expected to start Sunday against Miami, and the Colts (1-0) are promoting rookie Kerwynn Williams, their seventh-round draft pick, from the practice squad to the active roster. Former first-round pick Donald Brown also could see more action.
Ballard was Indy's top rusher in 2012. The rookie ran for 814 yards and two touchdowns but was best remembered for making the diving, twisting TD he scored on a 16-yard TD pass to beat Tennessee in overtime. Last week, Ballard ran 13 times for 63 yards and was 6 for 6 on blitz pickups.
He declined to talk with reporters Friday in the locker room.
But his teammates were supportive.
"Unfortunately, it's the game of football and it's not the first time it's happened to somebody on this team this season," Brown said. "Unfortunately, it probably won't be the last, either. It's a very tough injury and you hate to see somebody who puts in the work like he did, to see that happen to somebody like that. But next man up and you have to keep going."
Tight end Dwayne Allen missed practice again with a hip injury but Pagano said he was probable for Sunday's game against Miami. Linebacker Pat Angerer (concussion) was a full participant at practice for the third consecutive day.
Linebackers Kavell Conner (ankle) and Jerrell Freeman (quad) did limited work and are listed as questionable. Linebacker Erik Walden (hamstring) returned to full work after being limited Thursday. Walden also is listed as questionable. Receiver David Reed (concussion/quad) did not practice and has been ruled for Sunday's game.