Bill Gates: "I Will Miss Steve Immensely"

When Senna died, Prost stated that "a part of himself had died also", because their careers had been so bound together.[40] Senna had also felt the same when Prost had retired at the end of 1993, when he admitted to a close friend that he had realised how much of his motivation had come from fighting with Prost.

http://en.wikipedia.org/wiki/Alain_Prost#Rivalry_with_Ayrton...