Back, hip slow Cowboys' Roy Williams

IRVING, Texas -- The Dallas Cowboys had one wide receiver return to practice from injury before promptly losing another Tuesday.

Roy Williams missed Tuesday's practice with a strained lower back and a hip flexor. Team officials don't believe these ailments -- which flared up during Saturday's preseason game against the Houston Texans -- are serious and held Williams out of practice as a precaution.

Rookie Dez Bryant returned to practice for the first time since suffering a right high ankle sprain on July 30. He fielded punts with the scout team during the open media period Tuesday.

Cowboys owner and general manager Jerry Jones expects Bryant to go full speed in Tuesday's practice, and there is a slight chance he will play in Thursday's preseason finale vs. the Miami Dolphins.

Jones said Bryant would play only if other starters are participating, and coach Wade Phillips has already stated that starting quarterback Tony Romo will not play.

Jones said Bryant should play in the regular-season opener Sept. 12 at the Washington Redskins.

Several other players that had been sidelined because of injuries returned to practice Tuesday: safety Gerald Sensabaugh (shoulder), Keith Brooking (shoulder) and Marcus Spears (knee).

It's doubtful if those players will play vs. the Dolphins.

Starting offensive linemen Kyle Kosier and Marc Colombo did not practice as they are still recovering from knee surgeries.

Backup tight end John Phillips was scheduled to undergo knee surgery Tuesday. He will be lost for the season and has been placed on injured reserve.

Calvin Watkins covers the Cowboys for ESPNDallas.com. You can follow him on Twitter or leave a question for his weekly mailbag.