It ranks as one of the most memorable – and imitated – moments in sporting history. Back in 1981, a young John McEnroe, sporting a headband and frizzy hair, was so furious at the Wimbledon umpire Edward James's refusal to rule his serve in that he uttered the immortal line "you cannot be serious" before subjecting, or perhaps treating, the centre court crowd to a tirade of ill-tempered invective.
But new evidence today suggests that McEnroe could have had a point after all. True, his assertion that he had spotted chalk dust flying up from the line might not have justified his description of the match official as an "incompetent fool", but it seems it was certainly more than mere gamesmanship designed to put off his opponent, Tom Gullikson. Research carried out by a motion-perception scientist, Professor George Mather of the University of Sussex, suggests that players have an unusual ability to judge the position of a fast-moving ball. Based on data gathered from Hawk-Eye, a virtual-reality system that recreates a speeding shot's trajectory, he reveals that players can locate the position of a ball bouncing at up to 50m/sec to within a few centimetres.
However, there is some good news for the much-maligned Mr James, as the study finds that umpires tend to be more accurate than the players – though both are unable to place the ball exactly right every time.
"The analysis reported in this paper finds that the vast majority of challenges can be explained by perceptual limitations. When a ball bounces very close to a court line, the brain is unable to locate its position with sufficient precision to reach a correct decision on every occasion, so both players and line judges are bound to make errors," it concluded.
McEnroe went on to beat Gullikson and win the singles – exacting revenge on his temperamental opposite, the Swede Bjorn Borg. And so notorious was the incident that, when McEnroe came to finding a title for his autobiography, there was no surprise when it reached bookshops – Serious.