Prescott completed 7 of 8 passes for 108 yards and a touchdown, a 32-yard strike to receiver Dez Bryant on the opening drive.
Colts' backup quarterback Scott Tolzien started for Andrew Luck, who remains sidelined with a right shoulder injury. Tolzien completed 10 of 14 passes for 70 yards and led the Colts to a field goal in his five first-half drives.
Indianapolis evened the score 7-7 with defensive end Lavar Edwards returning a 15-yard fumble for a touchdown as linebacker Barkevious Mingo stripped Dallas backup Kellen Moore, who went 10 of 21 for 131 yards.
Two drives later, Moore led the Cowboys on a nine-play, 66-yard scoring drive to take a 10-7 lead after a 25-yard Dan Bailey field goal with 7:26 until halftime.
Indianapolis kicker Adam Vinatieri tied the game 10-10 with a 33-yard field goal on an eight-play, 52-yard drive that featured backup running back Marlon Mack rushing three times for 20 yards. Mack gained 45 yards on five carries as the Colts' leading rusher. The Cowboys outgained Indianapolis 257 to 104 in the first half.
Defensive end Margus Hunt blocked a 45-yard Sam Irwin-Hill field goal in the third quarter. Cornerback Darryl Morris recovered at the Colts 34-yard line. Mack rushed for 23 yards to set up Vinatieri's 42-yard field goal to give Indianapolis a 13-10 lead.
Cooper Rush led the Cowboys on two consecutive touchdown drives with a 19-yard touchdown pass to receiver Noah Brown to take a 17-13 lead with 1:32 in the third quarter, a six-play, 76-yard drive. The second was a 3-yard pass to receiver Lance Lenoir to give the Cowboys a 24-13 lead with 8:46 to play. Rush completed 8 of 9 passes for 92 yards and two touchdowns.
Colts quarterback Stephen Morris threw an 18-yard touchdown pass to receiver Fred Brown to narrow the lead to 24-19 after a failed two-point try with 0:57 in the game.