Lauda sought out Bernie Ecclestone on the grid in a bid to have the tunnel flooded as well. The tunnel was dry but coated with oil from the previous days' use (as well as from the historic cars which were on the program that weekend) which Lauda explained had turned it into a fifth gear skid pad when the cars came racing in carrying the spray from their tyres in the morning warmup. Ecclestone used his power as the head of the Formula One Constructors Association to do exactly that, with a local fire truck called in to water down the only dry road on the track. Pole-sitter Prost led the race from the start, while first corner contact between Ferrari's René Arnoux and the Renault of Derek Warwick pitched Warwick's car into the fence on the outside of St. Devote and into the path of his team-mate Patrick Tambay. Both drivers suffered leg injuries; Warwick bruised his left leg while Tambay broke his leg after his car's suspension punched through the carbon fibre monocoque, causing him to miss the next round in Canada. Prost was passed on lap nine by Nigel Mansell, to lead a Grand Prix for the first time, when Prost's TAG engine was misfiring and he was delayed by both Corrado Fabi's stalled Brabham and Michele Alboreto's about-to-be-lapped Ferrari just before the tunnel (Prost actually hit a marshal who was pushing Fabi's car away but with no serious injury). 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 sliding on a painted white line, damaging his car and retiring from the race. Lauda disposed of Arnoux but Prost assumed the lead again, only to have the Toleman-Hart of Ayrton Senna, who had also passed the Ferrari, quickly closing in. Senna had started thirteenth in the generally uncompetitive Toleman, in the first Formula One street race in his rookie season, and was showing his wet weather skills that would become legendary. On lap 29, Prost waved to the stewards of the race to indicate that he felt the race should be stopped. He was also suffering from a major brake imbalance as his McLaren's carbon brakes were locking due to not generating enough heat in the conditions, the same problem that had caused Lauda to spin at Casino Square on lap