FORT WORTH, Texas - Greg Biffle's body was sore heading into the NASCAR Nextel Cup race at Texas Motor Speedway.

A little more than 24 hours earlier, Biffle ran over debris on the track during a practice session, cutting down his right-front tire and slamming hard into the wall. The hit destroyed a new Roush Racing Ford race car and had Biffle a little unnerved at the start of Sunday's Samsung/Radio Shack 500.

"There was a lot of pressure today," he said. "I put a lot of pressure on myself, but I stayed pretty calm inside the race car. I knew what I needed to do. I knew I needed to hit my marks and be easy on the right-front tire. I was conscious of how much brake pedal I was using all day."

He needn't have worried.

Biffle overpowered the rest of the 43-car field on the way to his second victory of the season and the fifth of his career.

The 35-year-old driver from Vancouver, Wash., easily turned aside a late challenge from Casey Mears and, best of all, kept well away from those unforgiving concrete walls lining the 11/2-mile oval.

"I was sore when I went to bed, sore when I woke up and I'm still sore," Biffle said, wincing. "It's been in the back of my head thinking about it ever since, but it hasn't slowed me down."

And, fortunately for Biffle, his backup No. 16 Taurus was the same car in which he won earlier this season in California, so he wasn't too concerned about being competitive.

Despite starting from the back of the field after switching to a backup car, Biffle wound up leading 219 of 334 laps.

He picked off cars two and three at a time early in the race, moving all the way to 15th by lap 26, slipping into the top a few laps later. He took the lead for the first time on lap 87.

Biffle kept pulling away from the rest of the pack, but the race was slowed by 11 caution flags, keeping him from turning it into a rout.

The leaders made their final pit stops on lap 298 after Tony Stewart's engine blew, setting his Chevrolet on fire and bringing out the yellow flag. Stewart sustained minor burns to his right leg and arm, was treated and released at the infield medical center.

Casey Mears, who had been running a distant second to Biffle in his No. 41 Chip Ganassi Racing Dodge, took only two tires during his stop and beat Biffle out of the pits to grab the lead.

There was an aborted restart on lap 304 when Dave Blaney spun between the first and second turns, but the green flag was displayed for the final time on lap 309. It took Biffle just three laps to work to the inside of Mears' Dodge and shot past into the lead.

"We might have had something for him with four tires there at the end, but we were making the call to try to win the race, not finish second," said Mears, who was also in a backup after crashing Friday in the opening practice. "I tried to run the bottom and we just couldn't run fast enough."

After Biffle regained the lead, it was no contest. He pulled away to win by 3.244-seconds - about 20 car lengths ahead of runner-up Jamie McMurray, Mear's teammate. Biffle is the ninth winner in as many Cup races at Texas. He hadn't finished better than 28th in two previous Cup races here.

Series points leader Jimmie Johnson was third, with Mears matching his career best despite fading to fourth. Johnson has finished in the top 10 in each of his seven starts this season. He came into Sunday leading runner-up Biffle by 160 points and will go into next Saturday's race at Phoenix 135 ahead of the race winner.

Johnson was followed by Sterling Marlin, another Ganassi entry, and Michael Waltrip.

Kurt Busch, the defending series champion, ended a string of crashes in three straight Cup races by finishing seventh, while former Texas winner and fan favorite Dale Earnhardt Jr. was ninth.

Jeff Gordon, coming off a victory the previous week at Martinsville and trying to win for the first time at Texas, was never a factor, finishing 15th.