By mid- it was becoming impossible to pacify the two warring drivers. Following a fall out in the aftermath of a broken promise between them at San Marino where Prost and Senna agreed before the race that whoever got to the first corner in front would not be challenged into that turn. After the restart following Gerhard Berger's crash, Senna outbraked Prost going into the Tosa turn and broke the agreement, something which angered Prost. Senna later denied making the agreement but Prost was backed up by Marlboro's John Hogan who had been with the drivers when the agreement was made. The result was that the two barely talked for the rest of the season. Prost angered Dennis when not only did he announce that he would be joining Ferrari for , thus ending a highly successful six-year stint with McLaren, but also with his public comments about the team and Honda allegedly favoring Senna at the Italian Grand Prix. Dennis then showed his anger in public (a rare event) after Prost, who won the race following an engine failure for Senna, dropped his winners trophy from the podium to the "Tifosi" showing how unhappy he was despite the win. Dennis flung the Constructors winners trophy at Prost's feet and walked off the podium (Prost was later made to make a public apology over his comments about his unfavorable treatment under the threat of being sacked before the season ended). The "cold war" between the drivers came to a head at the Japanese Grand Prix when, at Honda's home track, Prost and Senna had their infamous collision while fighting for the lead late in the race which took Prost out and led to Senna's disqualification and gave Prost his third World Championship.