 Complete the following phrase:  At first, the 1987 championship was a four-way battle between Williams drivers Nelson Piquet and Nigel Mansell, Lotus driver Ayrton Senna, and McLaren driver and defending two-time champion Alain Prost. Eventually, it became a straight fight between Piquet and Mansell, who between them finished with nine wins from the seasons sixteen races. Mansell took six wins to Piquets three; however, he only recorded three other points finishes while Piquet recorded nine including seven second places. The duel was settled in Piquets favour at the penultimate race of the season in 