Schlesser was working as a test driver for Williams when he gained his first taste of Formula One (F1) in early 1983 when he bought a drive in the RAM team's March-RAM 01-Cosworth. His first race was the non-championship Race of Champions at Brands Hatch, where he started last of the 13 entrants and finished 6th. One week later, at the French Grand Prix at Paul Ricard, he was the slowest of the 29 cars in qualifying and thus failed to make the grid. He did not take part in another F1 race for five years, though he continued to test for Williams, and was active in sports car racing.