LATROBE, Pa. -- A groin injury has sidelined Mike Mitchell for the first part of training camp but the Steelers, starting free safety said the setback is not a significant one.

“I can sharpen myself in the film room, take every mental rep [in practice] which I wouldn’t do if I was practicing,” Mitchell said Sunday. “Now I literally pay attention on every snap. To have [football] taken away it's kind of frustrating. It’s making me hungrier.”

Mitchell said he had never injured his groin before getting hurt between the end of offseason practices and the start of training camp. He wouldn’t offer any details on how he got hurt other than that it happened while he was preparing for his first training camp with the Steelers.

Mitchell, who signed a five-year, $25 million contract with the Steelers in March, has been standing next to Carnell Lake in practice to get the defensive backs coach’s view of drills and so he can ask Lake questions.

Coach Mike Tomlin said at the start of camp that Mitchell, who is on the physically unable to perform (PUP) list, will likely miss the first week of practice.

The biggest downside to Mitchell’s injury is it cuts into the on-field work he will get with strong safety Troy Polamalu. The two only practiced together during minicamp last month since Polamalu didn’t take part in the organized team activities.

It is critical that the two build a strong rapport, but Mitchell said that won't be an issue.

“I know the playbook very, very well and you’ve just got to get out there and practice and when I’m back, we’ll be fine,” Mitchell said. “But we talk a lot, and I think our relationship is getting better every single day. When you’ve got one of the best safeties in the league to play with, your job isn’t that hard.”