San Francisco 49ers star defensive linemen Nick Bosa and Dee Ford have each missed three weeks of practice, but head coach Kyle Shanahan is not concerned.

Shanahan said Wednesday he expects both players will be ready to go for the season opener against the Arizona Cardinals on Sept. 13 (via Matt Maiocco of NBC Sports Bay Area):

“They’re not coming back today, but I’m not concerned,” Shanahan said. “I’d be very surprised if they’re not ready to go for Week One.”

Both Bosa and Ford have been dealing with leg muscle strains, though it seems they are being held out more as a precaution, than anything else.

The defending NFC champions are battling a number of injuries with less than two weeks to go until the opener, mostly on the offensive side of the ball.

All-Pro tight end George Kittle has been dealing with hamstring tightness, and rookie wideout Brandon Aiyuk suffered a hamstring strain just over a week ago.

Meanwhile, it remains to be seen whether Deebo Samuel will be active for Week 1 as he continues to rehab from surgery on a broken foot in June.

San Francisco retained most of its roster from last season, though DeForest Buckner was traded to the Indianapolis Colts in exchange for the 13th overall pick in the draft. Niners general manager John Lynch subsequently traded back to No. 14, where he selected South Carolina defensive tackle Javon Kinlaw as Buckner's replacement.

Ford and Bosa play a vital role in the 49ers' pass rush in their ability to set the edge and get in the backfield. Shanahan expects both edge-rushers will be available to wreak havoc on Cardinals quarterback Kyler Murray in Week 1.