FONTANA, Calif.-- Kurt Busch appeared set to earn his first Sprint Cup victory of the season before a caution with less than two laps remaining in the scheduled 200-lap race ended up foiling those plans Sunday at Auto Club Speedway.

The debris caution came out for what NASCAR said was a piece of metal between turns 3 and 4. Busch, no doubt in frustration of seeing a potential Auto Club 400 win slip away, radioed to his team: "WWE," a reference to the popular wresting shows and staged results.

Busch ended up pitting with most of the rest of the lead-lap cars, but he only took two fresh tires in anticipation of a two-lap dash to the finish that is NASCAR's "overtime" procedure.

Brad Keselowski, who had taken four fresh tires, ended up passing Busch for the win with the help of another caution for an obvious piece of debris -- a rear bumper cover that came off one of the cars.

Busch, in just his second race back after a three-race suspension, was diplomatic afterward.

"We just got hung out on the yellows at the end," Busch said. "When do you pit to put four tires on, when do you pit to put two tires on? That last restart I just didn't get the job done."

NASCAR Sprint Cup Series director Richard Buck said Sunday afternoon that the officials in race control had enough confirmation from their officials in the area that there was a piece of metal on the track. Because drivers tend to use the entire width of the speedway surface at this track, any piece of metal on the track surface typically results in a caution, Buck said.

Buck said the piece of debris was hit by another car after he had called for the caution.

"If there's any question whatsoever, we're going to throw the caution," Buck said. "There was a lot of paper flying around today, a lot of paper trash and plastic bags and those kinds of things. We got definite confirmation that it was debris and it looked like a piece of metal.

"It's strictly a process that we go through [to call a caution]. We don't have any favorites. We try to keep every emotion out of it. .. We feel very, very confident about our actions."

On the last lap, Greg Biffle spun on the frontstretch. NASCAR opted to let the race play out instead of ending the race under caution, and Biffle was able to drive away before the leaders had circled the 2-mile track. At Daytona earlier this year, NASCAR threw the caution on the final lap in order to get safety vehicles on to the track and tend to the drivers involved.

"Safety is No. 1; we always make our best effort to let it race back and we had a well over a mile [remaining]," Buck said. "The leaders were coming off of [Turn] 2. We had multiple people watching. ... Biffle got it started back up and got it turned around and headed off.

"We had two folks in the flagstand that were right there on top of it. We had a bird's-eye view from their perspective that there was no debris right there so we could let it come back to a natural finish."