Prost was back in the lead, Lauda was now second, and Senna was up to third. Then Lauda crashed out on Lap 24, and by Lap 27, Bellof had moved past René Arnoux into third. As Senna began quickly gaining on Prost, Bellof was catching Senna.

Image The Brazilian driver Ayrton Senna in 1989, five years after his debut Formula One season, during which he accomplished a stunning performance at the 1984 Monaco Grand Prix. Credit... Gilbert Tourte/Associated Press Photo

By Lap 29, Prost began waving at the race directors as he drove down the main straight, complaining that the track conditions were undriveable, calling for the race to stop. By Lap 31, Senna was only seven seconds behind Prost, who was now also having problems with his brakes, and continuing to protest.

Then Jacky Ickx, the clerk of the course, or race director, brought the race to a premature close on Lap 32, waving both the red flag and the checkered flag at the finish line.

Prost slowed down on the final straight, and Senna sped off past him, crossing the finish line ahead of the Frenchman and waving to the crowd, thinking he had won the race. In fact, when a race is halted prematurely, the final classification is taken from the previous lap completed by all contestants, which meant that it was the order from Lap 31 that counted.

Prost had won. Senna was outraged, feeling cheated of the victory. The Brazilian racing federation applied pressure. Ickx, who drove for the Porsche team in sports-car racing, was accused of giving Porsche, and Prost’s McLaren team, the victory. And because Ickx had failed to consult with the stewards over ending the race, his race clerk license was suspended.

Moreover, Prost was close to Jean-Marie Balestre, a fellow Frenchman who was president of the International Automobile Federation, or F.I.A., the sport’s governing body. So it was also claimed that the F.I.A. had assisted in Prost’s victory.

And yet Bellof’s drive was not only possibly more phenomenal than Senna’s — he had started 20th and finished third — but had the race continued for several more laps, Bellof might easily have won.