Despite Nelson Piquet winning the 1987 Drivers' Championship and Williams winning the Constructors' Championship, Honda decided not to supply the team with their engines, reportedly due to Williams's refusal to dump Nigel Mansell and hire Japanese driver and Honda test driver Satoru Nakajima (who debuted with Lotus in 1987), and instead supplied the McLaren team for . Prost had convinced Ron Dennis to sign Ayrton Senna to a three-year contract, which played a role in luring Honda (Senna's ability had been highly regarded by the Japanese giant when using their engines with Lotus in 1987 and both were keen to continue their association). However, this began the rivalry that pushed two of the sport's greatest drivers to unprecedented heights of success and controversy. McLaren-Honda dominated the season, winning 15 out of 16 races. Prost finished first or second in every race other than his two retirements at Silverstone and Monza. He won seven races and in total outscored his new teammate Senna by 11 points, despite Senna winning one more race than him. However, only the 11 best results from the season counted toward the championship total, and this gave Senna the title by three points. Prost went on to be a proponent of essentially the 1990s scoring system: all points counting toward the final results, with a race winner scoring 10 (rather than 9).