With Nigel Mansell still out of action with chicken pox and Martin Brundle (who had replaced him at Spa) racing elsewhere for Jaguar, the Williams team turned to its occasional test driver Jean-Louis Schlesser for the Italian Grand Prix.

Ayrton Senna took his 10th pole position of the year ahead of his McLaren-Honda team mate Alain Prost. The second row was all-Ferrari with Gerhard Berger ahead of Michele Alboreto as usual. The third row featured by the Arrows-Megatron drivers Eddie Cheever ahead of Derek Warwick while the fourth row had Nelson Piquet (Lotus-Honda) ahead of Thierry Boutsen's Benetton. Completing the top 10 was Sandro Nannini's Benetton and Riccardo Patrese's Williams.

In the race Senna and Prost took off at the front as usual with the two Ferraris chasing. The order did not much change until Prost retired with an engine failure on lap 35. Senna stayed ahead until the closing laps when he was lapping the midfield. Arriving behind 11th-placed Schlesser he dived for what he thought was a gap. Schlesser had been trying to keep out of Senna's way but found that he had nowhere to go and the two cars collided. Senna spun. He was out and not only was there a leader other than a McLaren. There was a Ferrari 1-2. Monza went mad. Berger duly won from Alboreto with Cheever third, Warwick fourth, Ivan Capelli fifth and Boutsen sixth.