Formula 1 has seen great champions. It has seen dominant cars and crushing defeats. But it has never seen anything quite like what happened when Ayrton Senna and Alain Prost shared a garage at McLaren and then spent three years trying to destroy each other on the track, in the press and inside the offices of the sport’s governing body. The rivalry did not just decide championships. It changed what Formula 1 is allowed to be.

The collision course was set the moment McLaren signed both men for 1988. On paper, it was an act of ambition. In practice, it was a declaration of war that neither driver had the temperament to avoid. Prost, four-time world champion, meticulous and relentlessly consistent, had already established himself as the benchmark against which every other driver was measured. Senna had spent years studying him, openly targeting him before he even reached Formula 1. “It was obvious, and he told me so many times,” Prost recalled years later. “I hadn’t realized how much he had focused on me before he made it to F1.”

Their first season together produced one of the most statistically dominant campaigns in the sport’s history: 15 wins from 16 races, split eight to seven in Senna’s favor. But the numbers obscured the real story. Prost began to suspect Honda, McLaren’s engine supplier, was giving Senna preferential treatment, a fear that hardened when a crate of engine components arrived at the factory marked “Special — For Ayrton.” The mutual respect that had briefly existed evaporated. What replaced it was something colder and more dangerous.

By 1989, any pretense of coexistence was gone. The title came down, as it would again the following year, to the Japanese Grand Prix at Suzuka. Senna needed to win to stay alive in the championship. He qualified 1.7 seconds faster than Prost, a gap that illustrated in raw terms the difference between them over a single lap. But Prost had prepared his race setup with characteristic precision and led from the start.

On lap 46, Senna moved to pass at the final chicane. Prost closed the door. Both cars tangled, stalled and stopped. Prost walked away. Senna pushed his McLaren back onto the circuit, drove to victory with a broken front wing and was then disqualified for rejoining via a shortcut after the collision. Prost was handed the title. Behind the scenes, FIA president Jean-Marie Balestre, a French national, was widely accused of steering the decision. Senna received a $100,000 fine, a suspended six-month ban and the official label of “dangerous driver” for daring to appeal. He called it a “manipulation of the championship.” McLaren’s Ron Dennis agreed.

Suzuka 1990 settled the argument in the most brutal way possible. Prost had moved to Ferrari. Senna arrived in Japan leading the championship, knowing that if both cars retired, the title was his. He had taken pole, but the FIA placed his grid slot on the less grippy, dirty side of the track. He asked for it to be moved. The answer was no. At the first braking zone of the opening lap, Senna simply did not brake, driving into Prost at full speed and eliminating both cars before the race had truly begun. He was world champion without crossing the finish line. Years later, he confirmed it had been deliberate.

The sport could not ignore what those two incidents had exposed. Formula 1 introduced stricter regulations on intentional collisions and unsportsmanlike conduct that remain in force today. McLaren rewrote how elite driver pairings are managed internally. The FIA restructured how stewarding decisions are made and communicated. Three seasons of personal warfare produced a rulebook that governs the sport three decades later.

Prost retired after 1993. At that season’s final podium, Senna publicly honored him, no irony, no score-settling, just respect. When Senna died at Imola on May 1st, 1994, Prost carried his coffin. “When he died, I felt that a part of me had died too.” They had spoken by phone twice a week in those final months. The men who tried to end each other’s careers had, somewhere along the way, become something close to friends. Formula 1 has never produced anything like it since.

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