"They broke each other's confidence," he said. "They both made commitments to each other several times, that was one that came into the public domain. There was tremendous tension and anger ... Those two were perfectly matched in deviousness."
The dispute reached its climax the year after at the penultimate race of the year in Japan, when Senna crashed into the Frenchman at the first turn, guaranteeing himself his second world title. The move disappointed Dennis.
"I remember looking at all the traces -- the brake and throttle pedal -- and you didn't need to be Einstein to work out what happened," Dennis said. "When he came back to the garage, I told him I was disappointed in him. He got it. He didn't have to say any more. I don't think he was particularly proud of what happened."