It is also uncertain whether he will play in Sunday's divisional round game against the Minnesota Vikings, but the Minnesota native expects to participate.
"Marion really wants to play in this ballgame," Cowboys coach Wade Phillips said. "If there's any way he could play he will, and I think he's better."
"We changed up the rotation throughout the year," Phillips said. "And the last part of the year we've hit it where we feel like we're comfortable with how they're playing. It won't change much if Marion is healthy."
The other 52 players on the roster were on the Valley Ranch practice fields during the portion of the workout the media is permitted to watch.
Pat Watkins, perhaps the Cowboys' best special teams player, worked with the first-team punt unit as a gunner. That's an indication that he's ready to play after spending the last four weeks on the inactive list with a knee injury.
The team will practice Thursday at Cowboys Stadium.