Ayrton Senna was a Brazilian racing driver who won three Formula One world championships. He entered Formula One in 1984 with the Toleman team, but after one season, he moved to Lotus. He spent three seasons with Lotus before moving to McLaren in 1988. Over the next five years, the intense rivalry between Senna and Alain Prost, a leading Formula One driver, came to the forefront, with particularly notable race incidents and collisions occurring between the two. Senna won all three of his world championships during his six seasons with McLaren, in 1988, 1990 and 1991. He wanted to move to Williams after 1992, but was prevented from doing so by a clause in Alain Prost's contract. He moved to Williams in 1994, but during the third race of the season, he was killed in an accident while leading the 1994 San Marino Grand Prix. He was among the most dominant and successful Formula One drivers of the modern era, and is considered by some as the greatest racing driver of all time.