Brabham were back up to two cars for the Canadian Grand Prix with Derek Warwick driving car number 8, but Arrows were a man down, Marc Surer having sustained serious injuries driving a rally car. The team had signed Christian Danner as a replacement but his contract could not be bought out until after the race, so he would stay with Osella in Montreal.
Derek Warwick must have been kicking himself for turning down the opportunity to replace Jacques Laffite at Williams in favour of remaining loyal to the Renault team. He endured a frustrating season that ended in unemployment, while Nigel Mansell, who took the Williams drive in his stead, had won three races already. He had been wanted by Lotus for 1986 – which would have been another potential winning move – but had been vetoed by Senna. When Elio de Angelis died, his phone rang to offer him the drive, at least in part (said Ecclestone) because he was about the only available driver who hadn’t called in the days after the crash to enquire…
Nigel Mansell took his first pole position of the year, lining up on the front of the grid alongside Ayrton Senna’s Lotus. Mansell’s Williams teammate Piquet was directly behind him in third, with Prost fourth ahead of old sparring partner Arnoux, going well in the Ligier. Rosberg was sixth, then Berger and 1981 winner Laffite on row 4, with the Brabhams of Patrese and Warwick rounding out the top ten. There was a nasty accident in the morning warmup when Patrick Tambay’s Beatrice-Lola suffered a suspension failure and the luckless Frenchman suffered leg injuries and was unable to start, so 14th place on the grid would also be empty.
When the lights went green, Mansell capitalised on his pole position to rocket into the lead with Senna in hot pursuit, with Prost nipping ahead of Piquet to claim third spot, chased by Rosberg, Arnoux, Berger and Alboreto having had a great start from 11th. Mansell immediately pulled away from Senna, who was leading a tight group behind him with Prost’s front wing tucked right up behind him. Rosberg soon got past Piquet too and joined in the battle for second; the three cars ran as one for a couple of laps until, on lap 4, Prost elbowed his way past at the hairpin forcing Senna to bounce over the kerbs and allowing Rosberg through as well. Senna’s lost momentum saw Piquet and Arnoux through as well and Berger was also looking for an opportunity.
By lap 6, Mansell had pulled out a lead of some five seconds over Prost, with Rosberg right on his tail and Piquet staying in touch a little way back, then another four seconds back to Arnoux and Senna. A few laps later and Rosberg was past Prost, squeezing through while the Frenchman negotiated a backmarker, and immediately began to pull away from his team-mate. Within a lap, he was right up behind Mansell, who had been held up by a recalcitrant Jonathan Palmer. The Finn was quicker past the Zakspeed and Prost likewise had little trouble. Rosberg was on a charge, and passed Mansell for the lead on lap 16, pulling out a small lead while Prost attacked Mansell. As the three came onto the home straight, Alessandro Nannini’s Minardi, just ahead, suddenly burst into flames and pulled off – the leaders passed harmlessly and Nannini hopped out of the car quickly enough, but it was another disappointing race for the little Italian team, who had already had to pull de Cesaris in for repairs. Danner and Fabi were already out, and Derek Warwick’s Brabham debut would end three laps later with an engine failure.
Then it was Rosberg’s turn to be held up by a backmarker – Phillippe Streiff’s Tyrrell – and allowed Mansell to catch up once more, while behind them Stefan Johansson was challenging Arnoux for sixth, with Senna having already gotten by for fifth. As Rosberg came up to lap Alan Jones, the veteran Australian tried to move aside but it was an awkward part of the track to do so and again he held Rosberg up, allowing Mansell right up onto the McLaren’s gearbox. As soon as the track allowed him, Jones got right out of the way, and Mansell dove in between the Lola and the McLaren to take the lead and lap Jones in one fell swoop, with Prost also getting past Jones and tucking up under Rosberg’s rear wing again. Rosberg wasn’t to be shaken off, though, and stuck with Mansell, while Alboreto had also disposed of Senna and was now in a three-way battle for the last point with Arnoux and Johansson that echoed the fight for the lead.
For lap after lap Rosberg harried Mansell for the lead with Prost keeping a watching brief behind, until the Finn peeled off for tyres on lap 26, heading out again after 13s, and Mansell made a better stop on the next lap. Prost now led, with Johansson now out, tripping over Johnny Dumfries while lapping the Lotus, which was on cold tyres having just changed them. Alboreto was next, then Prost – but a problem in the McLaren pit meant that the Frenchman’s stop took nearly 20s. Senna came in on lap 35, but Piquet, now second, remained out for lap after lap, maintaining a decent gap to Rosberg as the leaders threaded their way through heavy traffic. Finally, Piquet was in, a 10-second stop putting him back on the track in fourth. So after the stops had shaken out, the top four remained as they had been: Mansell, Rosberg, Prost, Piquet. Arnoux was non-stopping and was back ahead of Senna, now in sixth but chasing hard.
The race settled down after the excitement of the pitstops, with Senna’s pursuit of Arnoux and Piquet’s slow reeling in of Prost for third the only real bits of action on the track. Piquet got past Prost relatively easily on lap 46, and within a few laps both he and Prost were gaining on a fading Rosberg. Within one lap, Rosberg was down to fourth as Piquet and Prost both came past. On lap 56, with only 13 to go, Piquet had to pit for new tyres as his own were degrading rapidly, allowing Prost through into second and dropping him to fourth. Around the same time, as Mansell came through to lap the pair, Senna finally bludgeoned his way past Arnoux – never an easy man to pass at the best of times. Piquet wasted no time getting past Rosberg again on his fresh tyres.
And that was where they finished. Nigel Mansell took his second win of the season in commanding form, with Prost and Piquet joining him on the podium and Rosberg, Senna and Arnoux taking the minor points. In fact, the top six in the race were the top six on the grid, albeit in a different order.