The Colts held on as long as they could, but the dike finally broke, and when it did, it was a flood of points.
The Colts trailed 21-19 heading into the fourth quarter. They lost 54-19 as the Cowboys scored the fifth-most points in team history with a barrage of points in the final period.
Dallas improved to 9-3, while Indianapolis fell to 4-8-1.
The Colts had four turnovers in the fourth quarter and five for the game. The Cowboys scored 33 points in the fourth quarter, including a 38-yard scoop-and-score by ex-Colts safety Malik Hooker. (Hooker also had a first half interception.)
It was all fun and games for the Cowboys in the final stanza.
Dak Prescott was 20-of-30 for 170 yards, three touchdowns and an interception. CeeDee Lamb caught five passes for 71 yards and a touchdown, and Michael Gallup had four receptions for 23 yards and two touchdowns.