IRVING, Texas (AP) Dallas running back Darren McFadden is questionable for Sunday's game against Miami with a groin injury, and inexperienced backups could lead to some shuffling behind him.
McFadden was a limited participant in practice for the second straight day Friday after he wasn't listed on the first injury report of the week Wednesday.
Owner and general manager Jerry Jones said on his radio show that the team was being cautious with McFadden, whose career as the fourth overall pick by Oakland in 2008 was derailed by a litany of injuries.
He signed with Dallas a day after reigning NFL rushing champion DeMarco Murray left for Philadelphia in free agency.
''We didn't want to push anything, give it as much rest time,'' Jones said. ''No need to win it out here these next couple of days.''
After the Cowboys released Christine Michael this week, the only backups were undrafted rookies Rod Smith and Trey Williams, with their two combined carries this season.
Smith had both those carries with Seattle before the Seahawks waived him and the Cowboys picked him up. Dallas signed Williams off Washington's practice squad.
Because of that inexperience, the Cowboys (2-7) might be forced to activate Robert Turbin against the Dolphins (4-5) even though the fourth-year player has only been with the team since Wednesday. Dallas added him about a week after he was released by Cleveland.
''He has made a great impression,'' offensive coordinator Scott Linehan said Thursday. ''This guy is a veteran. He's played.''
Coach Jason Garrett said Turbin went to meetings and practice immediately after arriving and stayed late Wednesday studying the offense. He has 988 career yards without a touchdown. Turbin played all 16 games the past three seasons with Seattle.
''Line one is to get him ready to play as quickly as we can, and having said that the other two guys have to take advantage of their opportunity to show that they should be a part of this thing this weekend,'' Garrett said. ''It's a good, competitive environment.''
McFadden took over as the lead back with the team's first 100-yard rushing game of the season in a Week 7 loss against the New York Giants. After that, the Cowboys waived Joseph Randle, the starter for the first six games. They also lost Lance Dunbar to a season-ending knee injury.
He has averaged 24 carries and 91 yards in four games since taking over the lead role when Randle was injured against the Giants. McFadden has 494 yards and two touchdowns for the season.
''I feel so strong that McFadden has really got not only comfortable, but he's got comfortable with the offensive line and the nuances of their skills,'' Jones said. ''I'm really comfortable there, much more so than when we started the season with the way he's playing football.''
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This story has been corrected to show it is a groin injury for McFadden.