San Francisco 49ers offensive tackle Joe Staley left Sunday's game against the St. Louis Rams in the first quarter with a right knee injury.
The 49ers announced Staley would not return to the game, although there was no immediate report on the precise nature of the injury.
Staley said after the game he wasn't discussing his knee until tests scheduled for Monday provided him answers.
"I'm not talking about it. We will find out," Staley said, adding that he was "not going to say" what the current prognosis was as he left the stadium with the leg heavily braced.
Staley, who was named to the Pro Bowl each of the past two seasons, suffered the injury when he was hit low from the side. The 49ers were already playing without their other Pro Bowl lineman, offensive guard Mike Iupati.
The 49ers moved right tackle Alex Boone to the left side to replace Staley, and backup Joe Looney came in to play right tackle.