OXNARD, Calif. — Cowboys top draft pick Mo Claiborne will be out at least a week with a sprained medial collateral ligament in his left knee.It's a frustrating setback for Claiborne, the former LSU standout cornerback and sixth overall pick who missed all of the off-season because of wrist surgery.But he also breathed a sigh relief as the injury could have been worse. An MRI revealed no structural damage."I'm disappointed and angry because I missed a lot of reps in the past," Claiborne said. "I cant have those reps back. I can't get the reps that I need. It's a minor setback. I was worried at first. I'm not going to beat myself up over it."Coach Jason Garrett and defensive coordinator Rob Ryan said it's a setback for Claiborne to miss any time because he's a rookie and because of the high expectations the Cowboys have for him. But they believe he will stay engaged and be ready to jump back in when his knee heals."Well, we want our players out there practicing," Garrett said. "And we certainly want our rookie players out there practicing because they have the most ground to catch up. But as weve talked before, Morris is a smart football player. He understands things intellectually and he is able to carry the information from the meeting room to the field."He is going to stay engaged like the other guys who have been injured, stay engaged with the installation, with what is going on in terms of the coaching on the field, and we will get him back when he is healthy." The goal is for Claiborne to be ready for the season opener against the New York Giants on Sept. 5. He was getting a trial by fire going against wide receivers Dez Bryant and Miles Austin in practice. Now he has a lot of ground to make up.Any time you miss time, its tough. Especially when youre a young guy, Ryan said. I know hes going to be in there with Jerome Henderson and Joe Baker, two fantastic coaches, so he can stay up mentally that way. But no reps as good as the one on the field. Its going to be tough on him but hes got to do extra. Hes going to have to really work hard to be where we want him to be on opening day.For more Cowboys updates from training camp, go to our Cowboys Corner blog.