DENVER -- Offensive lineman Darrion Weems left Saturday's game with 13:29 to go in the second quarter with a possible concussion.
He was helped off the field by two trainers during the Broncos' contest against the 49ers.
Weems has been taking first-team reps since Ty Sambrailo injured his arm during training camp.
Rookie Connor McGovern replaced Weems at right guard on Saturday night.
Linebacker Corey Nelson appeared to injure his right wrist with 11:23 to go in the second quarter of Saturday's game.
A trainer stabilized Nelson's arm as they helped the third-year player off the field.
Nelson was hurt on a run play up the middle. He had been taking reps as Todd Davis' backup at the inside linebacker spot.
He is questionable to return.
UPDATE:Weems and Nelson have both been ruled out for the remainder of Saturday's game with a concussion and wrist injury, respectively.