Greg Biffle was proud of himself for an unlikely reason yesterday after winning the NASCAR race at Michigan International Speedway.

"The guys did a great job and I didn't make any mistakes, which is pretty unusual for me to race an entire day and not make any mistakes," Biffle said after pulling away from teammate Mark Martin for an easy victory in the GFS Marketplace 400 in Brooklyn, Mich.

Biffle, the only driver to win both the Busch and Craftsman Truck series championships, has struggled through most of his 65-race Nextel Cup career, finishing 20th in points last year as a rookie and failing to become a contender this season. He had just one top 10 finish in the first 19 races of 2004.

But things began to change earlier this month, with finishes of fourth at Pocono and sixth at Indianapolis before a disappointing 35th-place run a week ago on the road course at Watkins Glen.

"It's been tough at times this season, but I knew we could be in Victory Lane this year," Biffle said. "We've got this 16 car ironed out."

Martin and crew chief Pat Tryson chose to take only two tires on their final pit stop, while Biffle and the rest of the leaders took four. That gave Martin track position, but he was unable to come close to chasing down Biffle's Ford.

Biffle pulled steadily away from Martin's Taurus in the closing laps, beating his Roush Racing teammate to the finish line by 8.216 seconds -- nearly half the front straightaway on the two-mile oval.

"I was a little bit concerned because you never know what Mark Martin has up his sleeve," Biffle said. "He's always an aggressive racecar driver. . . . Thank goodness he took two tires. I knew it was over then."

The driver from Vancouver, Wash., led a race-high 73 of the 200 laps and averaged 139.063 mph, slowed by a Michigan record-tying nine caution flags.

Martin, who is making a strong run at a spot in NASCAR's new 10-race championship playoff, lost ground when he was penalized after a crewman failed to get a lug nut tightened on his left rear tire during a pit stop on Lap 130.

The four-time series runner-up, leading before that stop, fell to 23rd for the ensuing restart after being penalized by NASCAR.

There are only three more races remaining before the field is set for the "Chase for the Cup," with the top 10 drivers in the standings racing over the last 10 events for the title. After the race Sept. 11 in Richmond, NASCAR will reset the points, with the leader only five ahead of the runner-up and 45 in front of the 10th-place driver.

The points race tightened up yesterday when Jimmie Johnson -- who took the lead with a fourth-place run here in June and led by 232 points just three weeks ago -- had an engine failure for the third straight week and finished 40th. Hendrick Motorsports teammate Jeff Gordon moved to the top.

The four-time series champion, who last led the points at the end of his championship run in 2001, is now 68 ahead of Johnson. Dale Earnhardt Jr., a disappointing 21st yesterday, is 139 behind.

In the battle for the bottom of the top 10, Martin moved to 12th in the standings, just 33 points behind rookie Kasey Kahne, whose fifth-place finish yesterday moved him ahead of Evernham Motorsports teammate Jeremy Mayfield into 10th.

* IRL: Dario Franchitti shook off a potentially dangerous pit mishap and used a caution midway through the race to make up ground, going on to win the Honda 225 at Pikes Peak International Raceway in Fountain, Colo.

Franchitti, who held the lead four times for a total of 128 laps, including the final 63, went into the pits on Lap 85 for four new tires and fuel. As he started to pull out of the pits, fuel man Mike Miller had trouble getting the hose disconnected from the car and was clipped by the rear tire.

Miller wound up with a twisted knee and Franchitti lost about 10 seconds, allowing three drivers to pass him. But the Scottish driver took advantage of a yellow flag to clear debris on Lap 120, caught up to the leaders and passed Sam Hornish Jr. 12 laps later.