The Cowboys are optimistic Martin will be ready for the season opener against the Carolina Panthers Sept. 9.
The two-time first-team All-Pro apparently suffered a hyperextended left knee in Saturday's preseason contest against the Cincinnati Bengals. Cowboys owner Jerry Jones said he was optimistic that Martin's injury wasn't serious.
Martin is one of the league's top interior offensive linemen. Dallas drafted him 16th overall in 2014.
The 27-year-old hasn't missed a start in his four NFL seasons.