SANTA CLARA, Calif. -- San Francisco 49ers defensive end Nick Bosa suffered a calf injury in practice Thursday that is expected to cost him a few weeks, sources told ESPN's Adam Schefter and NFL Network's Ian Rapoport on Friday.
Bosa will not play in Sunday's game against the Arizona Cardinals as the 49ers work to determine whether the five-time Pro Bowler needs to be placed on injured reserve, sources said.
Returning to start the season from a torn ACL in his right knee, Bosa had played 70 snaps in the first two weeks combined. He was preparing to play against Arizona in a Week 3 that would have been almost exactly a year since he tore his ACL against the Cardinals.
He was listed as a nonparticipant for Wednesday's practice with the designation of "resting player/knee," but the 49ers added the calf to the knee designation Thursday and Bosa did not practice or do his usual weekly media session on Wednesday or Thursday.
Bosa's injury is the latest and perhaps biggest hit to a ravaged 49ers defensive line. The Niners placed defensive tackle C.J. West (knee) on injured reserve this week and have lost defensive end Sam Okuayinonu (foot) and tackle Alfred Collins (patellar tendon) to IR from injuries suffered in practice the first two weeks. Rookie defensive tackle James Thompson Jr. is dealing with a high ankle sprain that will cost him three to six weeks, and rookie edge rusher Romello Height has a broken hand that has kept him out of practice this week. Height has an "outside" chance to play against the Cardinals, according to coach Kyle Shanahan.
All of those injuries plus a long list of wide receivers dealing with ailments have the Niners already trying to figure out who can go on injured reserve and who can't because they can designate only eight players to come back from that list.
"There's a lot of variables there," Shanahan said Wednesday. "That's why it's not simple just to put everybody on IR return because then eventually you're not going to get one back. We're going to run out of them eventually, so that's what we're trying to balance out, see how those guys are this week. ... It's complicated and we've got to guess."
Without Bosa, the 49ers' healthy and available defensive ends are Keion White, Khalid Kareem and Ogbo Okoronkwo.
Another defensive end, Mykel Williams, is on the physically unable to perform list. He is expected to return to practice next week from a torn ACL suffered last season but can't play in a game until Week 5 when the 49ers visit the Seattle Seahawks.
