SPARTA, Ky. — Building a big lead during the final green-flag run and saving enough fuel to get to the end of the race, Brad Keselowski won Saturday night's Quaker State 400 NASCAR Sprint Cup race in a backup car.

Keselowski, who wrecked his primary car after tangling with Juan Pablo Montoya in Friday's first practice session for the race, picked up his series-best third victory of the season and the seventh of his career, all but assuring himself of a position in the Chase for the Sprint Cup.

Kasey Kahne rallied from an unscheduled pit stop on Lap 52 to finish second, followed by Denny Hamlin and Dale Earnhardt Jr. Jeff Gordon came home fifth, one spot in front of pole-sitter Jimmie Johnson, as Hendrick Motorsports drivers claimed four of the top six positions.

Ignition troubles ruined defending series champion Tony Stewart's night almost before it started. Stewart's No. 14 Chevrolet fell off the pace on Lap 26. By the time his team diagnosed and fixed the problem in the garage, Stewart was 35 laps down.

A bad night got worse for Stewart-Haas Racing on Lap 210, when Ryan Newman, Stewart's teammate, blew his engine, spun in his own oil and slammed into the outside wall in Turn 2, with Regan Smith hitting the wall behind him.

Clint Bowyer, last week's winner at Sonoma, was the innocent victim of contact that jeopardized his seventh-place position in the standings. Shortly after a restart on Lap 155, Bowyer was racing in close quarters with Newman, on new tires, and Joey Logano, who took fuel only during a pit stop under caution on Lap 150.

With a huge run off Turn 4, Newman clipped the back of Logano's Toyota in the tri-oval, turning him into Bowyer's Camry. On Lap 166, Bowyer brought his car to pit road, fearing he had a tire losing air. Bowyer lost two laps in the process and fell to 32nd in the running order.

But a cycle of green-flag stops and a free pass as the highest-scored lapped car returned Bowyer to the lead lap under the caution for Newman's wreck, and the driver of the No. 15 Toyota salvaged a 16th-place finish.