Legendary tennis coach Paul Annacone says it is 'madness' to try to diminish the achievements of Rafael Nadal because he is so good on clay.
Nadal equalled the all-time men's record of 20 Grand Slams by winning his 13th French Open crown this month.
Some, though, have claimed that since such a large proportion of his titles have come on clay, his achievement shouldn't be held in the same regard as Federer's.
Annacone, though, who coached Federer and Pete Sampras during an incredible career, strongly disagrees.
“I understand the concept, but just considering that having won a Grand Slam 13 times could be a flaw in some way is madness,” Annacone told Tennis Magazine Italia.
“Indeed, I believe it can be considered the greatest achievement in the history of the sport. It is a goal that I cannot even think can be beaten.”
The Grand Slam race feels so important as many tennis fans and media consider it to be the definitive factor in deciding who should be remembered as the greatest of all time.
Annacone, though, has a different take on it.
“I don’t believe in the concept of ‘greatest of all time,'" he explained.
"I think we can debate, if anything, the 'most successful', who has achieved the most in their career.
"And to do this we can consider yes, the Slams won, the weeks spent at the top of the ranking, the number of Masters 1000 tournaments, the Davis Cups …”
“Most people tend to consider Grand Slam wins as the most important meter, and so do the players themselves.
"But I’m not sure: for example, once Pete Sampras told me that his biggest success was not the 14 Slams, or the 7 Wimbledon’s, but the 6 years in a row as number one in the world at the end of the year."
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