Packers ILB Desmond Bishop is no stranger to calf injuries, but that doesn’t make this one any easier to endure.

Bishop, who pulled both calves last season, strained the right one running on his own the weekend before training camp began. He hasn’t been able to practice yet and is starting to get a little stir crazy.

“I wanted to run out there and hit somebody,” Bishop said Saturday, according to ESPNMilwaukee.com. “But I had to tone it down and be smart about it, and when my time comes and it’s fully healed, then I’ll get out there and play.”

His frustration is understandable. He missed three weeks in 2011 with a similar injury, though he said this one is “not as bad as it was last year. So that’s a positive. It just kind of sprang up.”

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Bishop said he didn’t have a timetable for a return and was leaving that up to the team’s doctors and trainers. He insisted the injury was a “minor setback” that wouldn’t keep him out of the regular season opener -- at home on Sept. 9 against the 49ers.

Meantime, second-year ILB D.J. Smith has been taking Bishop’s training-camp reps with the first team and sparkled. Smith, undersized at 5-foot-11, replaced the injured Bishop in the lineup last year, too, and he was a pleasant surprise, racking up 27 tackles and an interception in three games. During Thursday’s practice, he made one nice interception in 7-on-7 drills and later broke up a pass in team drills that a teammate picked off.

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For Packers updates, follow James Carlton on Twitter at @CBSSportsNFLGB.