Colt McCoy's return to Texas trumped Tony Romo's return to the game.
McCoy led Washington on a drive to set up Kai Forbath's 40-yard field goal in overtime and Dallas was unable to answer after Romo returned from an injury to his surgically repaired back, sending the Redskins to a 20-17 victory Monday night that ended the Cowboys' winning streak at six games.
McCoy, the former University of Texas star playing at the home of the Cowboys for the first time since his final college game in his home state, drove the Redskins to the winning points.
The Cowboys had one last chance, but didn't get a first down. Romo's final pass, on fourth down, was knocked away by Bashaud Breeland.
Romo left after getting sacked by Keenan Robinson in the third quarter. He lay motionless for several minutes but returned for the final Dallas drive of regulation.
Coach Jason Garrett said X-rays were negative and Romo had a back contusion.
McCoy was 25 of 30 for 299 yards.
Cowboys running back DeMarco Murray extended his NFL record with an eighth consecutive 100-yard rushing game to start the season. He had 141 yards rushing and 80 yards receiving.