Dale Earnhardt, dominating the NASCAR season, won a rain-shortened Southern 500 at Darlington (S.C.) International Raceway and collected $64,650.

The victory was Earnhardt's 10th in 21 races this season, bringing his 1987 take close to $1.2 million.

The race, which started a few minutes late as officials tried to dry the track from a light morning rain, was halted on the 202nd lap because of a thunderstorm. The race was scheduled for 347 laps on the 1.366-mile oval.

Earnhardt, whose Chevrolet started No. 5, led for 109 laps in winning his second straight race and the 30th in his career. He has a 583-point lead over Bill Elliott in the Winston Cup points race.

Rusty Wallace was second and Richard Petty third.

Davey Allison, the first rookie to win the pole at Darlington, spun out in turn four on lap 165, prompting a nine-lap caution. Allison's Ford blew a tire, spun completely around and tagged the wall. He was second at the time.

As Allison was sliding down the track, Mike Potter spun in the corner. Lake Speed, running fourth, and Benny Parsons slammed into Potter's car. No injuries were reported . . .

Nelson Piquet drove his Williams-Honda to an unprecedented fourth victory in Formula One racing's Italian Grand Prix at Monza and bolstered his lead in world championship points.

In a Brazilian-vs.-Brazilian finish, Piquet, 35, edged Ayrton Senna, in a Lotus-Honda. Nigel Mansell, the British teammate of Piquet, was third.

Piquet's third victory of the season and 20th of his career gave him 63 points after 11 races in the 16-round championship. Senna has 49 points and Mansell 43.

The winner covered the 50 laps (180.2 miles) at an average of 145 mph . . .

In Lexington, Ohio, Roberto Guerrero, capitalizing when Bobby Rahal was knocked out of the lead in a bumping incident 10 laps from the end, took his second Indy-car victory in the Escort 200. Guerrero won $67,410 and set a race record by averaging 107.431 mph.