OXNARD, Calif. -- A hamstring injury will keep Dallas Cowboys safety Matt Johnson out for at least a week if not more in training camp, continuing a trend that started soon after he was drafted in 2012.

Johnson suffered the injury in a pursuit drill in Sunday's practice, ending his day. It is the same leg he injured in the spring during organized team activities that kept him off the field. He missed most of his rookie season with recurring hamstring injuries and did not play last season because of foot surgery.

"Yesterday I was talking to my brother and stuff and I had a pity party, and you can't do that because it's not going to solve anything," Johnson said. But I just don't know. I've done everything I could -- stayed late, get here early, rehab it. I've done more in the month off that we had from the summer than I ever have in my life. Not as far as overworking it but as far as trying to get it ready. The conditioning test, felt fine. The first couple three days, felt good. I felt really good warming up I was like, 'You know what I'm going to give it all I had,' and ... it wasn't anything bad, but it's just frustrating knowing you can't got 100 percent and in the NFL you have to go 100 percent."

Johnson had an MRI on Sunday that revealed a strain. Coach Jason Garrett said defensive tackle Terrell McClain (ankle) could miss a week or so. Darius Morris (hamstring), Will Smith (groin) and Ben Gardner (shoulder) did not take part in the walkthrough. Executive vice president Stephen Jones said he hoped Gardner could practice in the afternoon.