DOVER, Del. (AP) — 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, 20th and 17th in the final standings in his two years on the circuit, leads them all this season.