Prost's teammate, local hero Nigel Mansell, took pole position and led before retiring with a gearbox failure nine laps from the end.
The win, Prost's third in succession and fourth of the season, gave him the lead of the Drivers' Championship, two points ahead of Senna.
Claudio Langes was seventh in the other, unrevised EuroBrun, with Bertrand Gachot a distant eighth in the Coloni after its engine destroyed itself yet again.
He was overtaken (against team orders, and to Mansell's chagrin) by Alain Prost and remained in second until his gearbox failed completely on lap 57.
On race day, he retired after damage was sustained in a collision with the Benetton of Alessandro Nannini on lap 27, whilst his team-mate Thierry Boutsen reached the podium and finished second.
Then racing with a broken exhaust header he charged hard, eventually passing Gerhard Berger for 3rd and for a time being the fastest driver on the track before retiring on lap 48 with a fuel leak.