The 1984 Monaco Grand Prix held at Monaco on June 3, 1984 amidst heavy rain, was one of the most contentious in Formula One history, and announced the emergence of at least two new stars. Alain Prost took the first of his four victories at the circuit
After a 45-minute rain delay, Pole-setter Prost led the race from the start, while contact between René Arnoux and Derek Warwick pitched Warwick's car into that of his team-mate Patrick Tambay. Both drivers suffered leg injuries, and Tambay missed the next round in Canada.
Prost was passed on lap nine by Nigel Mansell, leading a Grand Prix for the first time, when Prost was delayed by Corrado Fabi's stalled Brabham just before the tunnel. Mansell pulled away from Prost at around two seconds per lap, before going off six laps later on the run up to Casino Square after hitting a painted white line, damaging his car and retiring from the race.
Prost assumed the lead again, now from Ayrton Senna, who, in his first Formula One street race in his rookie season in a generally uncompetitive Toleman car, was rapidly catching him. On lap 29, Prost waved to the stewards of the race to indicate that he felt the race should be stopped. He waved again on lap 31 as he passed the start/finish line. The red flag to stop the race was shown at the end of the 32nd lap after clerk of the course Jacky Ickx decided that conditions were too poor for the race to continue. Senna passed Prost's slowing McLaren at the finish line, but according to the rules, the positions counted are those from the last lap completed by every driver - lap 31 , at which point Prost was still leading.<ref name="Autocourse1">Hamilton, Maurice (1984)) Autocourse 1984-85 p.141 Hazleton publishing ISBN 0-905138-32-5</ref> The stoppage was controversial, as it benefitted Prost with a Porsche-designed engine, and was made by Ickx, a Porsche employee in sports car racing. Ickx was suspended from his race control duties for not consulting with the stewards over his decision before making it. The rain was not falling as hard at this stage as it had previously been.
Had the race been allowed to continue until 75% of the laps, full points would have been awarded and Prost could have had 6 points from a 2nd place instead of 4.5 points from the win. Prost would eventually go on to lose the championship to Niki Lauda by half a point.
Senna and Mansell were not the only new driver to run near the front - Stefan Bellof finished third and had been closing on both Senna and Prost.<ref name="Autocourse1" /> The Tyrrell team's results were erased later in the season due to weight infringements.