Hammy strain delays Richard Sherman's comeback 'at least a week'

SANTA CLARA, Calif. -- San Francisco 49ers cornerbackRichard Sherman'scomeback from a torn Achilles took a slight detour on Sunday.

The Niners announced that Sherman will miss this week of practice and the team's preseason opener against the Dallas Cowboys on Thursday night as he deals with a right hamstring strain.

"We're definitely going to rest him at least a week," 49ers coach Kyle Shanahan said. "We don't think it should be long term. It's Grade 1, it's a little higher than we expected, so we've got to be careful with that."

Sherman appeared to suffer the injury in Friday's practice when he was covering wide receiver Pierre Garcon during team drills. Garcon caught a pass over the middle with Sherman in pursuit. As the play came to an end, Sherman took a tumble to the ground and stayed down for a moment as he clutched at his leg.

Sherman left that practice with what Shanahan then described as "tightness" in the hamstring but further tests showed it to be a little bit more serious than anticipated.

The hamstring strain comes in the middle of a camp in which Sherman has been working his way back from the right Achilles injury he suffered in November. With Sherman unavailable on Sunday, Tyvis Powell and Greg Mabin rotated in his spot with the first-team defense.

Shanahan and the Niners are hopeful Sherman can work back into the mix next week, but Shanahan made it clear at the beginning of camp that Sherman won't be rushed and everything he does will be with the idea of having him ready for the Sept. 9 opener against the Minnesota Vikings.

"I just want to see him get comfortable," Shanahan said at the start of camp. "It's different with Richard. There's lots of guys on our team we're real excited about and we think have a chance at a real good future and some guys who have had some success. But Richard is one of our few guys who has done it for a longer time. We've all played against him, we know what Richard is, and Richard is also a guy who I think we trust how he thinks, how he works. We know it's important for him to get out there as anyone in this world. He's someone we're going to communicate to a lot.

"A lot of it is up to Richard. Now, we've got to make sure if Richard is being a little too aggressive, it's our job to pull him back a little bit. But we've got to communicate the right way because, really, all I really care about Richard is him getting himself back to being Richard by Week 1, and if he can't do it by then, then just be honest with us because it's a matter of time when he gets back, and we just want to make sure we're smart with that and don't have a setback."