LONDON (AP) -- Twenty years after Ayrton Senna's tragic death, Ron Dennis still struggles to speak about the special bond he shared with the Formula One great.
Dennis, whose McLaren cars took Senna to three Formula One world titles, rarely delves publicly into his memories of a man who ''was so good for the whole time he was on the planet.''
Senna's death left Dennis devastated and the McLaren CEO still regards it as a private and complex affair, preferring to keep his emotions to himself. But as the 20th anniversary of Senna's passing is observed this week at the Imola track where he had his fatal crash on May 1, 1994, Dennis remembered one of the most fruitful collaborations in the history of the sport.
Dennis signed Senna to McLaren in 1987 on a day he will never forget. As negotiations neared conclusion, Senna and the McLaren boss could not agree on the money.
''We were arguing over half a million dollars, and I came up with the idea of us flicking a coin to decide,'' Dennis said in an in-depth interview with McLaren Mercedes website. ''But Ayrton's English wasn't so good at the time, so there was a five-minute conversation about the details. I had to draw pictures on a piece of paper. I just wanted to find a way forward. So the coin was thrown into the air, spinning. It landed and it went off like a rocket! You could hear it rattling under the curtains, I pulled them back and I won the bet!''
That episode speaks volume about Dennis and Senna's playful mindsets. It also marked the beginning of a five-year relationship, sometimes marred by feuds and disagreements, but mostly made of joy. During his time at McLaren, Senna triumphed in 35 grand prix races.
Senna left McLaren at the end of 1993 to join Williams and was killed in only his third race for the team when the 34-year-old Brazilian crashed on the seventh lap of the San Marino Grand Prix.
Over the years Senna drove for McLaren from 1988-92, the moments of fun Dennis shared with a man who was not exactly famous for his mischievous side have a special place in his heart. Driven and focused at races, Senna was indeed game for a laugh with people he knew intimately.
When asked about his fondest memory of Senna, Dennis mentioned a bet he won.
''He gave me an envelope once, I still have it at home,'' Dennis said. ''The envelope's been opened, but when he gave it to me it had $10,000 in it, the result of a bet we made that I could not eat a container of chili in Mexico. Before he could pull the bet back, I wolfed it down. That was about the fourth time that he had lost a bet, a big one. And I can remember him giving the envelope of money to me, and saying he was never going to bet ever again, that I'd got him into betting and that it was not a good thing to do!
''That's a fond memory because getting a smile across Ayrton's face was not easy, but getting him to part with money was even more difficult!''
Dennis said one of the reasons many people consider Senna to be the greatest ever is because he died too early.
''I can see no positives from the fact that he had an accident and lost his life, but it means that you didn't see his decline,'' Dennis said. ''There are lots of drivers that stay in the sport too long and tarnish their greatness.''
On the track, Senna was ruthless as can be and infuriated many of his rivals, including French nemesis Alain Prost. Senna and Prost spent two years at McLaren together in 1988-89 and Dennis was there to witness first-hand their long-lasting feud. At Imola in 1989, Prost accused Senna of breaking a pre-race agreement but Dennis said both drivers were to blame.
''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.''
But according to Dennis, that was just a moment of weakness in an otherwise flawless career.
''He's remembered because he was just so unbelievably competitive,'' Dennis said. ''He was great, but he had good, human values. He had a few lapses in his life, but he was incredibly principled. And he was a good human being.''