Adrian Peterson was forced to leave the field early during training camp practice on Tuesday because of what appeared to be an injury to his leg.
The Vikings Pro Bowl running back went to the ground -- something that isn't supposed to happen -- during an inside run drill and was slow to get up. He limped to the sideline and attempted to test out his leg by jogging in place.
Peterson, 30, then got back into drills for one play before again walking to the sideline with athletic trainer Eric Sugarman. When team drills were complete, Peterson went to the locker room while the team continued to practice.
No immediate details were available about the exact nature of Peterson's injury. Peterson, who was limited to only one regular-season appearance in 2014, did not play in the Vikings' win over Pittsburgh on Sunday in the Hall of Fame game and is not expected to appear in any preseason games.