The Cowboys placed guard Ronald Leary and defensive end Anthony Spencer on the physically unable to perform (PUP) list Thursday.
Both players will be sidelined at the start of training camp until medically cleared.
The Cowboys also put defensive tackle Amobi Okoye on the non-football injury list.
Leary is sidelined with a strained hamstring that he injured during conditioning tests Monday at Valley Ranch. Coach Jason Garrett did not want the team to go through conditioning tests this year, but a few veteran players held them anyways.
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The extent of Leary’s injury is unknown at this point, but he is expected to be in one of the bigger battles during camp. He and Mackenzy Bernadeau are the two candidates to start at left guard.
Spencer is coming back from microfracture surgery on his knee and appeared in only one game last season.
Okoye, who signed with the team in May, has a personal medical issue and has not played since 2012 with the Bears.