United States GP, 1985

There was only a week between the Canadian and Detroit races but there was a big announcement with Ford agreeing to supply its turbocharged engine to Carl Haas's Beatrice team. The canceled Belgian GP was also rescheduled for September.

The entry was the same as in Montreal with Ayrton Senna on pole in his Lotus-Renault ahead of Nigel Mansell's Williams-Honda and Michele Alboreto's Ferrari. Alain Prost was fourth in his McLaren-TAG ahead of Keke Rosberg (Williams-Honda), Derek Warwick (Renault), Eddie Cheever (Alfa Romeo), Elio de Angelis (Lotus-Renault), Stefan Johansson (Ferrari) and Nelson Piquet (Brabham-BMW).

Senna took the lead at the start while Rosberg drove a stunning opening lap to pass Mansell, Prost and the slow-starting Alboreto. Senna soon began to struggle because of tire problems and on the eighth lap Rosberg took the lead. Senna went into the pits and dropped right back down the order, leaving the two Williams-Hondas to run 1-2. Alboreto was third having overtaken Prost but he soon fell behind de Angelis and when Mansell spun on lap 20 the Lotus moved to second, while Mansell rejoined under pressure from Johansson and soon fell behind the Swede as well. Prost disappeared at the same time with a spin and Mansell followed while Martin Brundle (Tyrrell) found his car to be very competitive and having overtaken Alboreto, profited from Mansell's disappearance to run fourth. De Angelis was then forced into the pits when he snagged a front wing while going through backmarkers. He was no longer a force. Alboreto in the meantime has repassed Brundle and on lap 30 he collided with backmarker Philippe Alliot's RAM. This meant that Stefan Bellof (Tyrrell) was up to fourth. And so it remained until lap 50 when Rosberg pitted to get some paper out of his radiators. He rejoined with new tires just ahead of Johansson and soon motored away again. Senna was making good progress now and challenging Alboreto for third but on lap 52 Senna made a mistake while trying to get ahead and crashed. Thus Rosberg came home the winner ahead of Johansson, Alboreto, Bellof and de Angelis with sixth place going to Piquet.