WATKINS GLEN (AP) - Just when Marcos Ambrose had about given up hope of winning again at Watkins Glen International, he began to slide.

Suddenly in his element on an oil-smeared track, the Australian road race ace came alive one final time Sunday, storming past Kyle Busch and Brad Keselowski in a fender-slamming last lap of a chaotic Sprint Cup race to win at Watkins Glen International for the second straight year.

“It wasn’t going to be handed to me,” Ambrose said. “I had to get myself back up there.”

Ambrose, who led eight of the 90 laps around the 2.45-mile, 11-turn layout, had been shuffled back to ninth after a late caution and quickly made his way back to third in less than 10 laps, behind only Busch and Keselowski.

After passing Keselowski for second, Ambrose still trailed Busch by 2.3 seconds and figured he was running for second as the laps wound down.

“I managed to fight my way past Brad and then I tried to chase Kyle down, but he wasn’t making any mistakes and he had a fast car,” Ambrose said. “I just burned my stuff up trying to get to him. I was thinking, ‘OK, it may be second place here.’ But then the oil came down and I slipped to third and I thought, ‘That’s not the plan.’ So I just put my head down and just kept trying.”

Oil had begun spewing from the No. 47 of Bobby Labonte, and it coated much of the track. With only one lap remaining, NASCAR did not throw a caution and Ambrose capitalized.

“It was absolutely chaos at the end,” Ambrose said. “I had really burned off the brakes. I couldn’t figure out where it (the oil) was coming from. It was just absolutely crazy.”

Desperate for a win to move back into contention for the Chase for the Sprint Cup championship, Busch skidded wide coming out of the first turn of the final lap and was bumped by Keselowski’s fast-closing No. 2 Dodge.

“Busch slipped up big in turn one,” said Keselowski, who apologized after the race on Twitter. “There was nothing I could do. It was just one big giant oil slick underneath his car. We all checked up and Marcos was right on my bumper. We all just about spun out.”

Keselowski took the lead after caroming off Busch heading uphill through the high-speed esses and Ambrose followed Keselowski through as Busch spun to the side, tearing up wads of sod.

Skidding through the corners, Ambrose and Keselowski, his left front tire spewing smoke from a fender rub, battled side by side and nose to tail all the way around. Both even went through the grass in the inner loop at the top of the esses but kept charging.

“I knew there was oil all over the bus stop (inner loop),” winning crew chief Todd Parrott said. “It looked like the cars went through the grass because there wasn’t any oil.”

Ambrose bumped Keselowski to take the lead on the back straightaway but slipped again in turn 10 as Keselowski tried to return the favor but was unable to drive past. Neither gave ground, and Ambrose forged ahead for good on the final turn, a hard right-hander, turning away Keselowski’s charge on the outside.

“I must have hit the oil one more time and he didn’t,” Keselowski said. “I thought I had him.”

“In the end, nobody knew what was going on,” said Richard Petty, owner of Ambrose’s No. 9 Ford. “They were slipping and sliding off the race track. Marcos might have known a little bit about it, but the rest of us didn’t. Marcos stayed with it all day. Everything fell our way.”

It didn’t for Busch, who led 43 laps and seemingly held a commanding lead heading to the white flag of the Finger Lakes 355.

“Kyle hit the oil,” said Dave Rogers, crew chief of Busch’s No. 18 Toyota. “The 47 broke. You can see him, he just went by smoking. He left oil down all over the track. Kyle hit the oil and it allowed the (No.) 2 to get to us.”

An angry Busch declined to speak to the media afterward.

Entering the race, Ambrose had one win and had never finished lower than third in four starts at The Glen for an average finish of 2.3 and an average green flag speed of nearly 120 mph. Both were tops in the series.

Jimmie Johnson was third to gain the points lead by one over Greg Biffle. Sonoma winner Clint Bowyer and Sam Hornish Jr. were next, giving Dodge, which is leaving NASCAR at season’s end, two in the top five. Dale Earnhardt Jr. spun late while running in the top 10 and finished 28th to fall from first to fourth in points, 17 behind Johnson.

Biffle was sixth, and Busch, Matt Kenseth, Regan Smith and Martin Truex Jr. rounded out the top 10. Ryan Newman finished 11th to move back ahead of Jeff Gordon into the second wild card slot. Kasey Kahne, who has two wins, holds the other. Gordon was also a victim of the oil, spinning late and dropping from inside the top 10 to 21st after having driven past Newman.

The top 10 drivers in the standings qualify for the 10-race Chase, and two wild cards are awarded to the drivers with the most wins outside the top 10 - provided they finishing 20th or higher in points.

Polesitter Juan Pablo Montoya, who broke the track record in qualifying, finished 33rd after being forced to pit when something broke in the right front of his No. 42 Chevy a third of the way into the 90-lap race. He had tracked Busch for the first 26 laps.

Last year, Ambrose beat Busch and Keselowski on a paint-trading, two-lap dash to the checkered flag. Ambrose passed Keselowski for the lead on the final lap and secured his first Cup victory when a violent crash involving David Reutimann and David Ragan precipitated a caution that prevented Keselowski from making one final challenge.

Busch had the lead in that race, and he learned his lesson well. With all three up front again on a restart Sunday with 16 laps remaining, Busch dived from third to first on the inside of the 90-degree right-hander, outbraking both Ambrose and Keselowski to take the lead for the first time since lap 26.

Busch, who took the lead from Montoya as soon as the green flag flew to start the race, kept Keselowski at bay off his back bumper, with Ambrose seven car lengths back, and pulled out to a 1-second lead as Ambrose challenged Keselowski for second.

Ambrose finally got past him in the inner loop on lap 81, but he was 2.3 seconds behind Busch and seemingly running for second until the dramatic finish.