Like Imola, the Monaco track had been slightly amended, giving a slower kink at the harbour section, dubbed the Nouvelle Chicane. The entry list was the same as in San Marino two weeks earlier, except that Patrick Tambay now had the same Ford Turbo engine as team-leader Jones, and would hope that the Detroit company had solved the overheating problems that had led to the Australian’s retirement at Imola. Meanwhile there was some buzz about Ayrton Senna, who had been reported as saying he had signed for another team for 1987, and the smart money was on Ferrari.
San Marino winner Alain Prost took his first pole of the year to break Ayrton Senna’s run, lining up alongside Nigel Mansell with Senna’s Lotus in third. Nelson Piquet, the third member of the triumvirate who had locked out the top three spots so far, had had a dreadful time in qualifying and was down in 11th place. Fourth on the grid was Michele Alboreto, and fifth was an impressive Gerhard Berger, fresh from his maiden podium in Italy. Patrese was looking good in an improving Brabham in 6th, with Laffite 7th, Tambay 8th in his new Lola-Ford, Rosberg 9th and Brundle 10th in the Tyrrell. With a reduced grid of 20 for the race, there were six non-qualifiers: both Minardis, both Osellas, Rothengatter’s Zakspeed and – a shame given his previous good form – Johnny Dumfries’ second Lotus, plagued with gearbox gremlins. Bringing up the rear of the grid was Elio de Angelis, his qualifying likewise ruined by technical hitches.
As the cars set off for the parade lap, Jacques Laffite stalled and got away last, while Tambay had to use the spare car due to an oil leak in his race car. When the real start came, the lights went green and everybody raced towards the first corner at Ste Devote, the scene of many a first-lap fracas as 20 cars try to squeeze through all at once. This year, though, everyone made it through, and in the process Senna got ahead of Mansell, while street-circuit specialist Rosberg got a great start to slot in 6th behind Berger. The Finn was up to fourth by the time the field arrived at Loews, but Alboreto would prove a tougher prospect. The Ferrari was handling evilly on the street circuit and the lead trio were pulling away, but Rosberg couldn’t find room to get past.
Prost, meanwhile, was slowly pulling out a lead over Senna over the course of lap 2, a gap of 2 second by the end of lap 2. Further back, Alan Jones and Phillippe Streiff had a coming-together at Tabac and the Australian was out, while a marshal pushing the Tyrrell out of the way was very nearly hit by Prost’s McLaren – the Frenchman kept his car running and continued with the race. Behind Prost, two-car battles were taking shape; Senna v Mansell for 2nd, and Alboreto v Rosberg for 4th, with Berger and Patrese scrapping for 6th behind them. On lap 10, the Brabham got past the Benetton and six laps later Rosberg finally made his way past Alboreto, going through at Ste Devote and immediately pulling away from the Ferrari at a rate of knots. Indeed, Rosberg soon arrived behind his former team-mate Nigel Mansell to set up a three-way battle for second place with Senna, and allowing Prost to pull out even further.
A five-car train just behind the points-paying positions was providing more entertainment as Brundle in 8th led Tambay, Streiff, Piquet and Laffite through the baclemkmarkers, with them all jockeying for position as well. While the TV cameras were concentrating on that, Keke Rosberg passed Nigel Mansell into third on lap 26 and set about Senna’s Lotus. Senna was held up by Boutsen’s Arrows, which allowed the Finn to close right up, just as Mansell came in for the first of the tyre-stops, rejoining 5th behind Alboreto. Rosberg was next of the major runners to stop, on lap 31, exiting in a rather tardy 13 seconds, behind Alboreto. Patrese came in on the same lap from 6th but overshot his pit and stalled, and had to be dragged back and restarted, which ruined his race and promoted Arnoux. Prost was now nearly 20s ahead of Senna but had a stop planned while the Brazilian was thought to be on harder tyres and planning to run through to the end – a stop for Prost would see him emerge behind Senna, on fresher rubber but still needing to get past on the narrow Monaco streets.
Eventually, he decided to come in, while his team-mate Rosberg passed Alboreto in an identical move to the one he used last time. Prost was in and out in 9 seconds and exited just behind Ayrton Senna, who was just arriving at the midfield battle between Johansson and Tambay, who were in turn lapping Palmer and Streiff. Both leaders made their way safely through to lap the Ferrari and Lola for the first time and the Zakspeed and Tyrrell for the second, but Senna was quicker and pulled out his lead to 7 seconds – only for Prost to promptly reel him in again as soon as he was clear. At half-distance, Alboreto toured into the pits to retired with a blown turbo, while Prost was crawling all over the back of Senna trying to find a way past. Realising he needed fresh rubber, Senna peeled into the pits on lap 42, a 10-second stop and Prost re-took the lead, Rosberg went through into second and Senna re-joined just ahead of fourth-placed Mansell. On fresh rubber, he rapidly pulled away from the Williams, while Rosberg tried to make an impression on the gap to Prost, only for the reigning champion (and winner of the last two Monaco races) to put in a series of fastest laps to keep the Finn well behind. Piquet, meanwhile, had made his way up to sixth after a frustrating race, only to lose it to a charging Jacques Laffite.
The order changed little over the remainder of the race as everyone settled in to their places, with the main drama in the closing stages provided by a lurid accident when Patrick Tambay clipped Brundle’s Tyrrell at Mirabeau on lap 68, launching himself through the air and smacking into the barriers right next to some shaken spectators, putting both cars out and narrowly missing Mansell as he came to lap them. Prost cruised apparently effortlessly to his third Monaco win on the bounce. Rosberg seemed to have put a shaky start to the season with his new team behind him with a fine drive to second place, with Senna third, Mansell fourth and the Ligiers of Arnoux and Laffite fifth and sixth. Nelson Piquet was a frustrated 7th.