Finishing the 68th lap of the Spanish Grand Prix, with four to go, Alain Prost saw Nigel Mansell in his mirrors and put his boost up for the pit straight. It prevented Mansell from getting by at that point, but soon he was through.
Thereafter the Williams swiftly hauled in Ayrton Senna's leading Lotus, failing to catch it by just 0.014s. It was the closest grand prix finish of all time, and afterward Prost apologised to Mansell for delaying him. He had thought Senna too far ahead to be caught, he said. If he had known, he would have let Mansell through.
That was April, and only the second round of the Formula 1 World Championship. By late October Prost had cause to rejoice that he had whopped up the boost that day in Jerez. If he had not, Mansell would almost certainly have caught Senna, passed him, won the race - and the title. You could say, if you wished, that Mansell lost the crown by 0.014s of a second.
If, if, if. In the end, a grand prix season always comes down to that. Remarkable, is it not, that in a championship trail involving 16 races, 1044 laps and 2970 miles, a title can be decided by a little incident here, a bodged tyre stop there, a row in a motorhome.