Ricky Stenhouse Jr. spent most of the afternoon running at the front, with Kenseth chasing the No. 17 Ford that he drove to victory last year at the newly resurfaced Kansas Speedway.
But Stenhouse was among several leading drivers, including Carl Edwards and Greg Biffle, who were forced to pit under green with about 50 laps to go. They were just getting back onto the track when the rear-bumper on Keselowski's car that had been hanging on by a thread finally came loose.
The metal clattered across the track and brought out a caution.
Kenseth beat Truex in the race off pit road - critical at Kansas, where a second groove didn't start to round into shape until late in the race. Kahne had them both in his sights, but by the time he moved into second place, Kenseth had more than a full second on the field.
"I felt like restarting fourth, I needed to get to third, to second and to first as quickly as I possibly could," Kahne said. "I got by Jimmie and when I got to Truex, I just went around him before he could block the move, but by then, Kenseth was already gone."