IRVING, Texas -- As the world waits and wonders about the availability of running back DeMarco Murray for Sunday’s game against the Indianapolis Colts, the right side of the Dallas Cowboys’ offensive line is missing its second straight day of practice.

Tackle Doug Free and guard Zack Martin are sitting out of Thursday’s practice because of ankle injuries suffered last week against the Philadelphia Eagles. Owner and general manager Jerry Jones said he has concerns about Free’s ability to play against the Colts, but he's more confident that Martin will be a go.

Coach Jason Garrett said it could be possible Free serves as the backup on Sunday behind Tyron Smith and Jermey Parnell even if he cannot start.

Murray is expected to take part in some team drills at today’s practice after he did not do so on Wednesday. He went through the same warmups, catching passes and taking hand offs, as he did on Wednesday during the portion of the practice open to the media.

Quarterback Tony Romo (back) and linebacker Rolando McClain (knee) returned to practice.

Linebacker DeKoda Watson (hamstring) and defensive tackle Josh Brent (calf) were not on the practice field.