SANTA CLARA, Calif. --
San Francisco 49ers running back
Jerick McKinnon tore his right ACL while making a cut on the last play of practice Saturday, the team confirmed Saturday.
Niners coach Kyle Shanahan said McKinnon made a cut on air and immediately went down awkwardly on a noncontact play.
Because McKinnon's injury was noncontact and because of how it looked, Shanahan acknowledged that there was immediate concern that it was ACL-related.
"Yeah, I mean anytime I watch someone feel their knee, there's always that concern," Shanahan said before an official diagnosis was announced. "But I have felt that way before, and it hasn't been [an ACL], so I'm not trying to [make this] the darkest moment in the world right now. We hope that we're wrong."
McKinnon missed most of the preseason with a calf strain suffered in practice Aug. 12. He had been working his way back but was expected to be ready for the Sept. 9 opener against the
Minnesota Vikings before Saturday's injury. In fact, Shanahan said Saturday was McKinnon's first time back working in live team drills.
McKinnon was expected to be the Niners' starting running back in the opener, a role he had been unable to grasp in his previous four seasons with Minnesota.
The Niners signed McKinnon to a four-year, $30 million deal in the offseason and had hopes of making him one of the focal points of their offense. The injury came just before teams had to trim their rosters to the league-mandated 53 players.
San Francisco released running backs Joe Williams,
Jeremy McNichols and
Jeff Wilson as part of those roster moves. With McKinnon out, more roster shuffling could be in the offing at running back.
For now, the Niners have
Matt Breida,
Alfred Morris and
Raheem Mostert on the roster at running back. Breida, who suffered a shoulder injury in the preseason opener that cost him the next three games, had his first day back working in team drills Saturday. Shanahan said Breida is "good to go" and will be fully involved in the Niners' practices next week.
Niners general manager John Lynch expressed optimism about the Niners' roster even with McKinnon gone.
"We've got a lot of good football players here," Lynch said. "We're proud of our 53-man roster, and next week we're going to be really excited looking to take on the Vikings."