Greg Biffle's surprising run to the top of Nextel Cup competition got a boost Sunday from a stunningly easy victory in a crash-filled race on the Monster Mile.

Biffle got his series-leading fourth win of the season to close within 46 points of pacesetter Jimmie Johnson. The victory in the $5.5 million MBNA 400 was Biffle's first at Dover International Speedway and the seventh of his career.

In a race slowed seven times for 33 of its 400 laps, Biffle won in part because he avoided traffic problems that resulted in hard crashes. Among those taken from the field were four-time Dover winners Jeff Gordon and Ricky Rudd, and Ken Schrader and Dave Blaney.

Biffle did crash once, but it was after the race. As crew chief Doug Richert was explaining that Biffle "drove the wheels off the thing," the winner smacked the wall hard during his burnout celebration.

Until this year, Biffle was largely overlooked among drivers for Roush Racing, which also fields cars for NASCAR great and four-time Dover winner Mark Martin; series champion Kurt Busch; former champion Matt Kenseth and exciting youngster Carl Edwards.

But Biffle, 17th and 20th in the final standings during the past two seasons, respectively, leads them all this season.

Biffle said the Roush organization's tight-knit approach is behind its success. He said his car wasn't so good leading up to the race until Kenseth's team prepared it with a new shock package.

"That's what teamwork is all about," he said.

He did make one decision on his own -- to take four tires on his final pit stop under green while most of the others were saving time by taking two.

"I said, 'I want four tires, and I don't care what happens,' " he explained. "I was prepared to put four on and race for the win."

Biffle started second because rain prevented qualifying Friday, forcing the field to be set by car-owner points. He bided his time over the first half of the race, then passed Elliott Sadler for the lead on Lap 241.

After that, the field became strung out, allowing Biffle an open track with few traffic problems. He wound up leading a race-high 150 laps on the high-banked concrete oval.

It was the fourth straight finish for Biffle in the top six, including a victory last month at Darlington.

Roush had another magnificent day, taking four of the top nine spots in the field of 43. It was the organization's sixth victory in 13 races this season; the only real competition for Roush this year has been Hendrick Motorsports, which has five wins between Gordon and Johnson.

Biffle's Ford beat the Chevrolet of Kyle Busch by 4.281 seconds. Martin was third, followed by Johnson in a Chevy and Rusty Wallace's Dodge.

The winner averaged 122.626 mph. There were nine lead changes among five drivers.

Brian Vickers, Kenseth, Ryan Newman, Kurt Busch and Sadler completed the top 10.

Gordon was spun out early in the race by Tony Stewart, and Rudd crashed in the wake of their contact. Blaney hit the inside wall on the backstretch and was fortunate not to be injured when he got sideways and was clobbered by a trailing Schrader on the 137th lap.

The race marked the halfway point toward the 26-race cut, after which only the top 10 drivers or those within 400 points of the leader will contest the championship over the final 10 events.

Greg Biffle basks in his fourth win after cruising through a crash-filled race at Dover; he trimmed Jimmie Johnson's Nextel Cup lead to 46 points.