The 1991 Canadian Grand Prix was a Formula One motor race held at Circuit Gilles Villeneuve on 2 June 1991. It was the fifth race of the 1991 FIA Formula One World Championship.

The 69-lap race was won by Nelson Piquet, driving a Benetton-Ford. Piquet took the 23rd and final win of his F1 career after old rival Nigel Mansell, driving a Williams-Renault, suddenly stopped halfway round the last lap while leading by almost a minute. Stefano Modena took second in a Tyrrell-Honda, while Mansell's team-mate Riccardo Patrese was third, having started from pole position. Piquet's win was the first for a car using Pirelli tyres since the 1986 Mexican Grand Prix when Gerhard Berger took Benetton's first ever Grand Prix victory and the last for the famed BMW turbo.

This was the last win for Pirelli as a tyre supplier in Formula One until the 2011 Australian Grand Prix.

Pre-race Between the Monaco and Canadian Grands Prix, Cesare Fiorio had been fired as team manager of Ferrari and had been replaced by Piero Ferrari. Meanwhile, John Barnard had left as Benetton's technical director; he was replaced by Gordon Kimball (father of future IndyCar driver Charlie Kimball).

On the driver front, Julian Bailey's funding ran out and he was replaced at Lotus by Johnny Herbert, who subsequently failed to qualify for the race, while Alex Caffi was out of action for Footwork as a result of injuries sustained in a road accident. His place was taken by Stefan Johansson.

Qualifying Pre-qualifying report As at the previous Grand Prix in Monaco, the pre-qualifying session was dominated by the Scuderia Italia Dallara cars, and the Jordans. With Dallara's Emanuele Pirro fastest ahead of his team-mate JJ Lehto, followed by Jordan's Andrea de Cesaris and Bertrand Gachot, there was over a second between the four pre-qualifiers and the rest.

Those who failed to progress to the main qualifying sessions included Olivier Grouillard, fifth fastest for Fondmetal, his best result of the season so far. The Modena team was starting to run into financial difficulties, and the performance of their Lambo cars was also slipping, as Nicola Larini and Eric van de Poele ended the session down in sixth and seventh positions. Slowest was Pedro Chaves in the Coloni, despite a new Hart-prepared Cosworth DFR engine.

Pre-qualifying classification Pos No Driver Constructor Time Gap 1 21 Emanuele Pirro Dallara-Judd 1:23.244 — 2 22 JJ Lehto Dallara-Judd 1:23.480 +0.236 3 33 Andrea de Cesaris Jordan-Ford 1:23.672 +0.428 4 32 Bertrand Gachot Jordan-Ford 1:23.719 +0.475 5 14 Olivier Grouillard Fondmetal-Ford 1:24.795 +1.551 6 34 Nicola Larini Lambo-Lamborghini 1:25.736 +2.492 7 35 Eric van de Poele Lambo-Lamborghini 1:26.900 +3.656 8 31 Pedro Chaves Coloni-Ford 1:34.475 +11.231

Qualifying report In practice Riccardo Patrese had a huge accident, walking away unhurt. In the qualifying sessions, Patrese took pole position from team-mate Mansell, out-qualifying him for the fifth straight race. Senna was third followed by Prost, Moreno, Berger, Alesi, Piquet, Modena, and Pirro.

Qualifying classification Pos No Driver Constructor Q1 Q2 Gap16 Riccardo PatreseWilliams-Renault1:37.5931:19.837 —25 Nigel MansellWilliams-Renault1:35.0651:20.225 +0.38831 Ayrton SennaMcLaren-Honda1:35.8431:20.318 +0.481427 Alain ProstFerrari1:36.0031:20.656 +0.819519 Roberto MorenoBenetton-Ford1:35.8971:20.686 +0.84962 Gerhard BergerMcLaren-Honda1:38.2231:20.916 +1.079728 Jean AlesiFerrari1:35.2571:21.227 +1.390820 Nelson PiquetBenetton-Ford1:37.3541:21.241 +1.40494 Stefano ModenaTyrrell-Honda1:38.2181:21.298 +1.4611021 Emanuele Pirro Dallara-Judd1:39.0171:21.864 +2.0271133 Andrea de CesarisJordan-Ford1:37.0971:22.154 +2.317123 Satoru NakajimaTyrrell-Honda1:41.1001:22.262 +2.4251316 Ivan CapelliLeyton House-Ilmor1:40.9061:22.443 +2.6061432 Bertrand GachotJordan-Ford1:38.3831:22.596 +2.7591524 Gianni MorbidelliMinardi-Ferrari1:39.7801:22.993 +3.1561625 Thierry BoutsenLigier-Lamborghini1:38.5171:23.040 +3.2031722 JJ LehtoDallara-Judd1:38.4351:23.040 +3.2031823 Pierluigi MartiniMinardi-Ferrari1:37.8641:23.125 +3.2881929 Éric BernardLola-Ford1:38.0131:23.260 +3.423207 Martin BrundleBrabham-Yamaha1:38.4051:23.516 +3.679219 Michele AlboretoFootwork-Porsche 1:41.1961:23.529 +3.6922230 Aguri SuzukiLola-Ford1:39.6961:23.585 +3.7482315 Maurício GugelminLeyton House-Ilmor1:38.6891:23.650 +3.8132411 Mika HäkkinenLotus-Judd1:42.9001:23.923 +4.0862510 Stefan JohanssonFootwork-Porsche1:49.0191:24.433 +4.5962626 Érik ComasLigier-Lamborghini1:39.6701:24.460 +4.6232718 Fabrizio BarbazzaAGS-Ford1:40.5551:24.491 +4.6542817 Gabriele TarquiniAGS-Ford1:41.9461:24.653 +4.816298 Mark BlundellBrabham-Yamaha1:39.8971:24.661 +4.824 3012 Johnny HerbertLotus-Judd1:39.1131:24.732 +4.895

Race Race report At the start, Mansell got away well and led Patrese, Senna, Prost, Berger, and Moreno. Berger went out on lap 4 with electronics problems, while Aguri Suzuki retired when his Lola caught fire. Moreno was out on lap 10 when he spun off, while Prost was suffering from gearbox problems. The Frenchman had managed to hold on while he engaged in a battle with teammate Alesi and Piquet's Benetton.

Mansell led Patrese and Senna on lap 25 when Senna retired, leaving Mansell and Patrese a long way ahead of the Alesi–Prost–Piquet battle. This ended Senna's thus far perfect season, capping his winning streak at 4. Prost retired shortly after with a gearbox failure on lap 27 and Ferrari's misery was compounded on lap 34 when Alesi's engine blew up.

The Williams drivers were now well ahead of the pack, but Piquet closed on Patrese, the Italian suffering from gearbox troubles of his own. In the late stages Patrese was passed by Stefano Modena in the Tyrrell. On the last lap, Mansell led from Piquet, Modena, Patrese, de Cesaris, and Gachot when he suddenly slowed to a halt at the hairpin. There were rumours that Mansell had failed to change gear for the hairpin and stalled the car, or that he had turned off the engine accidentally while waving to the crowd during the final lap. Mansell denied this, saying that the gearbox had gone into neutral as he shifted down, and Williams said that the car had suffered an electrical failure. When the car was returned to the pits, the engine was re-fired and the gearbox worked perfectly. Piquet thus took an unexpected victory for Benetton at the expense of his old rival Mansell, who was classified sixth. Jordan's five points, their first in Formula One, meant that they would no longer have to pre-qualify when the draw was reshuffled at the halfway point of the season.

The race was Nelson Piquet's 23rd and last win in Formula One, and Stefano Modena's second and last podium finish.

Race classification Pos No Driver Constructor Tyre Laps Time/Retired Grid Points 1 20 Nelson Piquet Benetton-Ford 69 1:38:51.490 8 10 2 4 Stefano Modena Tyrrell-Honda 69 + 31.832 9 6 3 6 Riccardo Patrese Williams-Renault 69 + 42.217 1 4 4 33 Andrea de Cesaris Jordan-Ford 69 + 1:20.210 11 3 5 32 Bertrand Gachot Jordan-Ford 69 + 1:22.351 14 2 6 5 Nigel Mansell Williams-Renault 68 Electrics 2 1 7 23 Pierluigi Martini Minardi-Ferrari 68 + 1 lap 18 8 26 Érik Comas Ligier-Lamborghini 68 + 1 lap 26 9 21 Emanuele Pirro Dallara-Judd 68 + 1 lap 10 10 3 Satoru Nakajima Tyrrell-Honda 67 + 2 laps 12 15 Maurício Gugelmin Leyton House-Ilmor 61 Engine 23 22 JJ Lehto Dallara-Judd 50 Engine 17 10 Stefan Johansson Footwork-Porsche 48 Throttle 25 16 Ivan Capelli Leyton House-Ilmor 42 Engine 13 28 Jean Alesi Ferrari 34 Engine 7 29 Éric Bernard Lola-Ford 29 Gearbox 19 27 Alain Prost Ferrari 27 Gearbox 4 25 Thierry Boutsen Ligier-Lamborghini 27 Engine 16 1 Ayrton Senna McLaren-Honda 25 Alternator 3 11 Mika Häkkinen Lotus-Judd 21 Spun off 24 7 Martin Brundle Brabham-Yamaha 21 Engine 20 24 Gianni Morbidelli Minardi-Ferrari 20 Spun off 15 19 Roberto Moreno Benetton-Ford 10 Suspension 5 2 Gerhard Berger McLaren-Honda 4 Injection 6 30 Aguri Suzuki Lola-Ford 3 Fuel leak 22 9 Michele Alboreto Footwork-Porsche 2 Throttle 21 18 Fabrizio Barbazza AGS-Ford 17 Gabriele Tarquini AGS-Ford 8 Mark Blundell Brabham-Yamaha 12 Johnny Herbert Lotus-Judd 14 Olivier Grouillard Fondmetal-Ford 34 Nicola Larini Lambo-Lamborghini 35 Eric van de Poele Lambo-Lamborghini 31 Pedro Chaves Coloni-Ford

Championship standings after the race

Drivers' Championship standings Pos Driver Points 1 Ayrton Senna 40 4 2 Nelson Piquet 16 1 3 Alain Prost 11 4 Riccardo Patrese 10 2 5 Gerhard Berger 10Source:

Constructors' Championship standings Pos Constructor Points 1 McLaren-Honda 50 2 2 Benetton-Ford 19 3 Williams-Renault 17 2 4 Ferrari 16 5 Tyrrell-Honda 11Source:

References