France's Alain Prost, driving a Renault turbo, won yesterday's French Grand Prix despite critical mistakes in the season's first major battle of pit stops.

Prost led for all but three of the 54 laps on the French Riviera track, with former world champion Nelson Piquet of Brazil taking second in his Brabham BMW turbo and moving into the lead in this year's title race after three of 16 events.

American Eddie Cheever scored his best result ever, placing third in the other Renault turbo despite a poorly balanced car.

For the first time, all the leading cars pitted for fuel and sometimes tires. Despite fears, there were no accidents during the stops, which are an innovation in European-style racing.

"I had stomach pains because I was so tense waiting for something bad to happen," Prost said after winning his sixth Grand Prix victory in 1 hour 34 minutes 13.913 seconds, at an average speed of 124.194 mph . . .

Gordon Johncock came back from a big deficit with the help of a caution flag and a high attrition rate to win the Indy-car half of the Kraco Dixie Twin 200s at Atlanta International Raceway.

Johncock, whose brakes locked up and sent him spinning down the pit road midway through the race, had moved all the way back to second, a lap behind leader Mike Mosley's March, when Mosley made a final pit stop and blew his engine on pit road just 14 laps from the end.

Johncock, the 1982 Indianapolis 500 winner, led the next time around the 1.522-mile high-banked oval, and beat second-place finisher Al Unser by 32 seconds, which translated to more than a lap . . .

In North Wilkesboro, N.C., Darrell Waltrip took the lead with a fourth of the Northwestern 400 completed and easily went on to win his first NASCAR Grand National race this season.

Waltrip, whose Chevrolet started 10th, passed pole-sitter Neil Bonnett on the backstretch on lap 126 and was never seriously challenged the rest of the way.

"We needed a win real bad," said Waltrip after winning his fourth straight race at the speedway. "I think we showed a lot of character today."