If Rafa Nadal wins the Australian Open title next Sunday, he could claim to be the greatest male tennis player of the modern era.
There are substantial factors to overcome, including the Melbourne heat, fierce rivals such as Roger Federer, Andy Murray and (especially) Novak Djokovic, as well as the Spaniard's relatively poor recent record in Australia, where he has made the final just once in his last four attempts.
But if Nadal lifts the Norman Brookes Challenge Cup in seven days, he will become the first man in the Open era (since 1969) to win all four Grand Slam tournaments at least twice. The others who achieved the feat - Rod Laver (1960-69) and Roy Emerson (1961-67) - did so outside what is known as the open era.
It's the ultimate measure of consistency and durability, across four surfaces.
Federer has won several titles in Melbourne, London and New York but only one at Roland Garros. Pete Sampras, Stefan Edberg and Jimmy Connors also never won in Paris, while Bjorn Borg was unable to win the Australian or US Opens. Ivan Lendl was consistent (two Australian Opens, three French Opens and a hat-trick at Flushing Meadows) but was continually frustrated on the Wimbledon grass. Djokovic is a Melbourne legend already (four titles in six years) but has yet to win the French Open and has won only once at SW19 and in New York.