Davey Allison won the Budweiser 500 at Dover Downs (Del.) International Speedway yesterday after his father Bobby had car trouble.

It was rookie Davey Allison's second career NASCAR Winston Cup victory and second victory this season. He won $46,600.

"I hated seeing him have problems," he said. "I was hoping he'd come in second."

Asked how he avoided tire problems that plagued many drivers, Davey Allison said, "Our guys worked really well on the tires and the car and we didn't have to do anything or abuse the tires."

American 200:

In Milwaukee, Mario Andretti and Roberto Guerrero each looked to be a sure winner, but Michael Andretti won.

The younger Andretti, Mario's 24-year-old son, picked up his second straight Miller American 200 win, the fourth triumph of his Indy-car career, while his father was in a nearby hospital undergoing precautionary X-rays and Guerrero was hiding his disappointment in his motor home.

Just a week earlier in the Indianapolis 500, the elder Andretti led 170 of the first 177 laps before a mechanical problem knocked him out of action.

Guerrero wound up second to Al Unser Sr. at Indy, but only after a faulty clutch led to his stalling on a late pit stop, costing him a shot at the victory.

Yesterday, Mario Andretti crashed when his rear wing snapped off while he was leading the race, and Guerrero's engine blew as he battled for the lead with the younger Andretti just 22 laps from the end.

Mario Andretti, 47, was taken from the car by track safety personnel and transported to Milwaukee County General Hospital for X-rays, which determined that Andretti suffered a non-displaced fracture of the tip of the spinus process. Dr. Steve Olvey called the injury "a sore neck" and said Andretti was released from the hospital and was expected to drive in Portland in two weeks.

Monaco Grand Prix:

Brazilian Ayrton Senna easily won the race in Monte Carlo in a Lotus-Honda.

Alain Prost of France, seeking a record 28th Formula One victory, ran third most of the race before dropping out with two laps left. Nigel Mansell of Britain, starting from the pole position, led for 30 laps before a turbo broke.

Another Brazilian, Nelson Piquet, finished second, 33.212 seconds behind Senna, and Michele Alboreto of Italy was third.

Prost, the two-time world champion and winner of the last three Monaco races, dropped out in the 76th lap with engine trouble. He never challenged for the lead and was more than 50 seconds behind Senna when he pulled off the course.

It was the fifth Grand Prix victory in 50 races for Senna. He had won two each of the past two years.