After intercepting a pass in team drills on Friday afternoon, linebacker Keith Brooking left the field with an apparent hamstring injury.
The severity of the injury wasn't immediately known, and no timetable has been set for a return.
The Cowboys have had a few players come down with muscle tweaks of late, most recently Tashard Choice, who is expected to miss at least two weeks with a calf injury. Safety Akwasi Owusu-Ansah suffered a cramp and had to come out of Thursday's afternoon practice. Running back DeMarco Murray tweaked his calf late in the summer and will start camp on the Non-Football Injury (NFI) list.
Many league observers had expected a rash of injuries during camp because of possible inactivity among the players during the NFL lockout, but it's impossible to say whether there's anything to that right now. Every training camp has its fair share of players coming up lame with strains and pulls.
Brooking is among the most durable and resilient players in the league. The 35-year old has played in 160 consecutive games, second-most among active linebackers.