Jordy Nelson has a torn ACL in his right knee but everything else is in tact.
Nelson will miss the remainder of the season for the Green Bay Packers.
"It was determined that WR Jordy Nelson sustained a significant right knee injury in yesterday's game at Pittsburgh," the Packers said in a statement. "He will miss the remainder of the season."
Nelson will need reconstructive surgery but should be back for the start of the 2016 season.
Nelson appeared to land awkwardly on his left knee and not the right knee. Nelson limped off the field under his own power.
"It's difficult to lose a guy like that in a meaningless game," Aaron Rodgers said after the game.