FRISCO -- In need of a quarterback to help get through Thursday's final preseason game, the Dallas Cowboys are bringing in Austin Davis for a visit Wednesday, according to a source.Rookie quarterback Dak Prescott isn't expected to play Thursday against Houston at AT&T Stadium. The only other healthy quarterback on the Cowboys' roster is Jameill Showers.The Cowboys have been looking to add a veteran quarterback to the roster after Tony Romo was lost for six to 10 weeks with a fractured bone in his back.If the Cowboys sign Davis on Wednesday, he could serve as Showers' backup Thursday against the Texans and then Dallas would have to make a decision on him by the final cuts deadline Saturday, when all NFL teams have to get down to 53 players.Davis, 27, was released Monday by the Cleveland Browns.