Cook (hamstring) has been ruled out for Sunday's game against the Bills.
Latavius Murray will take over as the lead back, with undrafted rookies Mike Boone and Roc Thomas providing depth. Cook is in clear danger of missing multiple games, as the Vikings will face the Rams on Thursday Night Football in Week 4. He was held out of practice Wednesday and Thursday, then limited to side work with the training staff during the portion of Friday's session open to the media.