Minnesota Vikings running back Adrian Peterson told ESPN on Wednesday that he will have surgery Thursday to repair a torn meniscus in his right knee and he could be out the rest of the season.

Peterson was injured late in the third quarter of the Vikings’ 17-14 victory over Green Bay on Sunday night in the first regular-season game at U.S. Bank Stadium. He has what he said is a “bucket handle tear.”

“I’m told that it’s a minimum of three, four months out and up to six months usually,” Peterson told ESPN.

If it’s on the shorter end, Peterson, 31, could return late in the regular season, which ends Jan. 1, and possibly for the playoffs. If it’s on the longer end, he’s out for the season.

Peterson, the 2015 NFL rushing champion, got off to a very slow start this season, rushing for just 50 yards on 31 carries in two games.