Coach Mike Sherman said that Diggs may have sprained his knee, but was awaiting further diagnosis from the team's medical staff.
Diggs' injury combined with rookie Brady Poppinga's pulled hamstring leaves the Packers thinner at the linebacker position. Poppinga sustained his injury during the team's first full-squad practice on July 26 and has yet to return to practice.
If Diggs' injury is a sprain, he could miss four to six weeks. Diggs, 27, is a veteran leader of the linebackers. Last year, he finished second on the team in tackles with 116 and one sack.
With Diggs out, the Packers scrimmaged without five of their starters on defense today. Grady Jackson (knee) and Cletidus Hunt (knee/shoulder) did not practice, and cornerbacks Joey Thomas (calf) and Al Harris (quad) also sat out.
Walker wants to play
Javon Walker's mind is willing, but his hamstring is weak. The wide receiver did not practice today, but says he will play in Thursday's exhibition opener against the San Diego Chargers and not play it safe by sitting out.
"No, I'm definitely playing the preseason game on Thursday," Walker said. "With football you can't play scared."
Walker also said that his contract situation has nothing to do with the hamstring injury, which he sustained in practice on Sunday. Walker skipped the team's off-season minicamps in protest of his contract, which has two seasons remaining. He feels he is underpaid and wants a new deal.
"That's way over with. I'm here now on the field," Walker said. "If that was a problem, I wouldn't be practicing. I'd still be sitting out, playing everything cautious. That's not a problem. That doesn't cross my mind. I think everything will happen for a reason. I just hope to go out now and have a great season."
Cornerback Jason Horton, safety Mark Roman and wide receiver Sam Breeden returned to practice today. Horton was bothered by a shoulder injury and Breeden a hip flexor. Roman injured his neck in a collision with Nick Collins Sunday in practice, but participated in practices today. Collins did not practice today after he woke up with a headache and some dizziness as a result of his collision with Roman on Sunday.
Others who did not practice today included defensive end R-Kal Truluck (hamstring); defensive back Chris Johnson (shin); offensive lineman Brad Bedell (hamstring); and running back Walt Williams (ankle).
Offensive tackle Chad Clifton did not practice in the morning. His wife, Candy, gave birth to the couple's first child on Saturday.