AVONDALE, Ariz. — Kurt Busch knew he had the best car Saturday night, but he had to keep coming from behind to prove it.

"It's probably one of our best wins," Busch said after holding off a determined Michael Waltrip in the NASCAR Nextel Cup race at Phoenix International Raceway. "You think you've got it put together, but something happens and you get behind. It says a lot for the team that we were able to overcome all the things that happened to put us behind."

Busch was able to forget all about being stiff and sore as he raced to his first victory of the season.

The defending NASCAR Nextel Cup champion led 219 of 312 laps on the mile oval, emphatically putting behind him a streak of bad luck that included crashes at four consecutive events, including an IROC race a week ago at Texas Motor Speedway.

Greg Biffle, the hottest driver on NASCAR's top circuit, was the only competitor able to challenge his Roush Racing teammate during the first half of the Subway Fresh 500, the first Cup race run under the lights at PIR. But Biffle, who won the Cup race last Sunday at Texas and took the checkered flag here Friday night in a Busch Series race, lost his shot at another win in the pits.

A caution period for debris on the track was extended by a brief power outage that took out the track's caution lights and forced NASCAR to stop the race for nearly 7 minutes. On the ensuing restart on lap 146, Biffle got by Busch, but it took only two laps for the eventual winner to slip by on the inside and regain the top spot.

That was it for Biffle, who collided with the car driven by Mike Bliss on pit road during the next caution period and wound up with extensive damage to the front of his car, including a hole in his radiator. The team tried to repair the damage but eventually gave up as Biffle was credited with finishing 41st.

Busch slipped back into the pack for a while during a flurry of caution flags and pits stops, but charged from ninth on a restart on lap 211 to regain the lead, passing Jeff Gordon for the top spot on lap 227.

Then Busch had to do it again.

This time, eight drivers remained on track when Busch and several other leaders pitted during a caution — one of nine in the race — on lap 240. Busch restarted ninth and began slashing through heavy traffic, moving steadily forward until finally driving past Michael Waltrip to take the lead for good on lap 269.

Waltrip tried hard to chase him down, nearly getting by on lap 299 before wiggling hard and then scraping the wall. He bounced off the wall twice more as he struggled to keep up with Busch.

"We just had a great car," said Waltrip, who got his third top 10 finish of the season. "I just ran out of brains there at the end and hit the wall a couple of times. I'd rather mess up trying, though. I did all I could do."

Busch held on the rest of the way, using lapped traffic to his advantage. He beat Waltrip's Chevrolet to the finish line by 2.315 seconds — about 10 car-lengths — for his 12th career victory. Jeff Burton was third, followed by Waltrip's teammate, Dale Earnhardt Jr., Vickers, Bobby Labonte and Carl Edwards.

It was the fourth victory in eight races this season for Jack Roush's teams, with Biffle winning twice and Edwards getting his first Cup victory.

"Kurt Busch gave them a clinic tonight," Roush said. "I was sure he was hurting his tires at the end, but he saved just enough."

Busch jumped from fourth to second in the standings, trailing series leader Jimmie Johnson, who finished 15th, by 173 points. Biffle slipped to third, 208 behind.

The start of the race was delayed about 30 minutes by a late afternoon rain shower, but there were no more weather problems.