The Packers announced Monday afternoon that Nelson will miss the entire season. Although the team did not specify Nelson's injury, a source told ESPN NFL Insider Adam Schefter that an MRI revealed Nelson tore his ACL, but everything else in his knee is intact.
"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."
Coach Mike McCarthy said after Sunday's game that he had hoped for good news after Nelson underwent additional tests Monday.
Nelson will need reconstructive surgery but should be back for the start of the 2016 season. He took to Facebook to thank his family, friends and fans.
That it was Nelson's right knee was a bit of a surprise, considering he appeared to land awkwardly on his left knee after a short reception on the game's opening drive. He limped off the field after the noncontact injury and walked to the locker room under his own power, but he did not return.
"You can't understand how something like that can happen on a play as simple as it was, but that's life in the NFL sometimes," Packers general manager Ted Thompson told Green Bay radio station WNFL on Monday.
"It's difficult to lose a guy like that in a meaningless game," quarterback Aaron Rodgers said after the game.
Nelson led the Packers last season with 98 catches for 1,519 yards and 13 touchdowns. He underwent offseason hip surgery but was cleared in time to start training camp the past month. Nelson will be 31 before the start of next season. He is under contract through the 2018 season.
His injury leaves Randall Cobb as the Packers' leading receiver. Cobb caught 91 passes for 1,287 yards and 12 touchdowns last season. Davante Adams, who caught 38 passes for 446 yards and three touchdowns as a rookie last season, likely will become the team's other starting receiver.
"Life in the NFL sometimes is who's the next man up. That's what we'll start focusing on," Thompson said Monday. "Certainly, we're not in any position where we think we can necessarily replace Jordy. Jordy is a wonderful player, wonderful person in the community and everything else. He'll continue to do that, but maybe we find two or three guys who can fill the role that he played."