Nigel Mansell led the race until lap 70, but then suffered a loose wheel nut and was forced into the pits, emerging behind Ayrton Senna. The pair duelled around Monaco for the final three laps but Mansell could find no way past, finishing behind the Brazilian.
First F1 victory for Ayrton Senna. He demonstrated his proficiency in wet conditions by finishing the race at least one lap ahead of every car, except second-place finisher Michele Alboreto.
Despite Senna stalled on the grid & had dropped to 14th place, he immediately made a charge through the field and managed to force his way through as leader Prost was trying to deal with a malfunctioning gearbox & a tricky wet/dry surface. With victory in the race, Senna clinched his first F1 title.