Ambrose passed Brad Keselowski for the lead during a green-white-checkered finish and then held it for his maiden victory in his 105th start in NASCAR's top series. He won three Nationwide races in a row at this track from 2008-10.
An incident involving Paul Menard in the closing laps setup the two-lap overtime finish. Pole sitter Kyle Busch held the lead for the final restart, but Busch and Ambrose both spun their tires, allowing Keselowski to move ahead of them for the top position. But Ambrose came storming back and made the winning pass in turn five on the second-to-last lap.
The race ended under caution for a horrifying multi-car crash involving David Reutimann, David Ragan, Tony Stewart and Clint Bowyer. Reutimann's car flipped around after he slammed hard into the turn two barrier on the final lap. No one was injured in the incident.
Ambrose, who became the fifth first-time race winner this year, placed himself in contention to secure one of the two wild card spots in the championship Chase. Four races remain before NASCAR's playoffs begin on September 18 at Chicagoland Speedway.