Rafael Nadal has already sealed the year-end number one ranking with almost three months of the 2010 season left.

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It is all the more extraordinary given that Nadal was being written off as a spent force at the start of the year. His season really took off at the start of the clay court season where he won all three Masters Series title, sparking an incredible five months in which he also claimed his fifth French Open title, a second Wimbledon and a first US Open title.

The one big title in the game Nadal has yet to win is the end of year ATP World Finals but few would bet against him going all the way in London in November.

"It has been an incredible season - one of my best ever, if not the best," Nadal said after being informed by the ATP that he was guaranteed to finish the year as world number one. "Winning the US Open together with Roland Garros and Wimbledon, as well as the three back-to-back Masters in Europe, was not easy."

It is the second time that he has claimed the year-end number one spot after 2008.

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