At the front of the pack Prost had taken the lead when Senna pitted. Shortly after it began to rain, which was a major advantage for Prost and those drivers that hadn't pitted, as they would only have to do one less stop. Senna began to catch Prost as the track became wet and on lap 21 as the rain became heavier Senna overtook the Frenchman on the approach to the Spoon Curve. At the end of the lap Senna's lead was over two seconds and the pair pitted for wet tyres. Senna pulled away rapidly and by lap 27 his lead was over thirty seconds. Prost then left the track at the first corner, but was able to rejoin the race behind Senna, one lap down. Unable to lap Hill Senna was re-passed by Irvine, who had already been lapped, but was chasing Hill for fourth position. Irvine, who was also still on wets, challenged Hill going into the first corner, but was unable to complete the move, whilst Senna was being held up by the pair. Senna lost fifteen seconds behind the pair once he had forced his way through. At the end of lap 42 both Senna and Prost pitted for Slicks and Senna's lead was back up to twenty-four seconds.