SANTA CLARA (AP) — There’s growing concern about Joshua Garnett’s knee injury, 49ers coach Kyle Shanahan said Friday, after the guard missed the last five practices of training camp.

“Josh said that he doesn’t feel right, so that’s always worrisome when a player says he doesn’t feel right,” said Shanahan. “And I know Josh is getting a few second opinions. So waiting until our doctors talk to other people and see what conclusion they come to.”

Garnett began camp in a heated competition to start at right guard after missing all of 2017 following surgery on the same right knee last August. The team said Garnett banged knees with a teammate July 28 and he was expected to return this week.

Part of the concern is the uncertainty surrounding the injury, which the team initially called “not significant.”

“It depends who you talk to,” Shanahan said. “That’s what we’re trying to find out and that’s what he’s trying to find out. Josh went through a lot last year with his knee.”

San Francisco signed Jonathan Cooper and Mike Person in the offseason to also be in the mix at right guard.

Cooper, who had offseason knee surgery, hasn’t participated in full-team drills yet after returning to individual drills earlier this week. Person has been given the majority of the work with the starters while second-year player Erik Magnuson has also been involved.

NOTES: CB Richard Sherman sat out the second half of Friday’s practice after feeling tightness in his hamstring, Shanahan sa6id . Rookie WR Dante Pettis was given the day off after tweaking his groin . Rookie LB Fred Warner sat out Friday after suffering a chest contusion earlier in the week . DE Jeremiah Attaochu (groin) was also given the day off . The 49ers will have the day off Saturday before returning to practice Sunday.