Ayrton Senna's last duel with Alain Prost Aug 23 2012
Alain Prost retired from F1 racing for the final time in 1993, with his last race coming at the Australian Grand Prix in November. He finished second in the race to his fierce rival Ayrton Senna but handily won the World Championship to the runner-up Senna. But the two of them raced for one final time in December of that year...driving go-karts.
Predictably, the pair took it very seriously: four-time world champion Prost having tested extensively before the event; Senna, a three-time title holder, having a kart shipped to Brazil so that he could practise.