Reynolds underwent neurological exams each day since being struck in the helmet by a 95-mph Collin Balester fastball in Tuesday's game against the Washington Nationals.
"We're confident that he'll be fine," interim manager Kirk Gibson said Sunday morning. "I'll be really sure to make sure that he's feeling fine as the game goes on, and keep an eye on him. If he isn't, we'll get him out of there."
Reynolds, who was available to pinch-hit and play defense Saturday, camped out in Gibson's office following the 6-5 win, hoping to convince his skipper that he was ready.
Reynolds (.220, 25 home runs, 69 RBIs) hit sixth and manned the hot corner.