There were big changes happening at Ferrari with Sporting Director Cesare Fiorio having been fired after the Monaco GP (as a result of a public rift with driver Alain Prost). Fiorio was replaced by Piero Lardi Ferrari. There were also changes at Benetton with technical director John Barnard falling out with team boss Flavio Briatore and leaving. Gordon Kimball was appointed technical director instead. Alex Caffi was out of action with Footwork after breaking his jaw in a road accident and his place was taken by Stefan Johansson, while Julian Bailey stood down at Lotus and was replaced by Johnny Herbert.

In qualifying in Canada Riccardo Patrese took pole position from his Williams-Renault team mate Nigel Mansell. Ayrton Senna was third in his McLaren while Alain Prost was fourth in the Ferrari. Roberto Moreno (Benetton) was fifth with Gerhard Berger (McLaren) sixth, Jean Alési (Ferrari) seventh and Nelson Piquet (Benetton) eighth. The top 10 was rounded off by Stefano Modena's Tyrrell-Honda and the fastest of the pre-qualifiers Emanuele Pirro in his Dallara.

The system of pre-qualifying was developed in response to the increasing number of teams competing in Formula 1. It was decided that 30 cars were the maximum safe limit to compete for 26 grid places. The cars which had to pre-qualify were decided at the beginning and the midpoint of each season. The 26 cars which had achieved the best results in the previous two-half seasons automatically entered official qualifying for the race. All the other cars had to pre-qualify for the 4 other slots available for official qualifying. Those that failed to pre-qualify just went home.

At the start Mansell took the lead from Patrese and the pair ran in 1-2 formation for the first 40 laps. Eventually Patrese had a puncture and had to pit and so dropped to third place behind Piquet. Mansell continued to lead in dominant fashion until the very last lap when, waving to the crowd, he allowed the revs to drop too low and the car stalled. With no power to drive the hydraulic system he could not select a gear. He was out with less than a lap to go. Mansell's old rival Piquet swept to a joyous victory while Modena was a delighted second. Patrese was third with Andrea de Cesaris and Bertrand Gachot in the Jordans fourth and fifth and Mansell classified sixth. Of the rest the McLarens and Ferraris all went out with mechanical trouble.