Federer won two Grand Slams in 2017, his first since 2012, to make it 19 for his career.
He is the most successful men’s player in history, three ahead of Rafael Nadal and now five clear of Pete Sampras.
He does trail Margaret Court on 24, Serena Williams on 23 and Steffi Graf on 22 and is level with Helen Wills on 19.
But Roger Federer is expected to add to his 19 this season with the Australian Open starting on Monday.
Now aged 36, and having gone five years without a Slam win, questions have been asked about his future in the sport.
But Sky Sports tennis expert Croft thinks he’s playing as well as he ever has and believes he wants to set a record so high that no one can catch him.
With Nadal five years younger and only three behind, she believes he will carry on playing until his body stops.
Novak Djokovic is also seven Slams back so could come into contention if he gets his elbow right.
“You know what I think is keeping him going, for the majority of his career now he’s been playing with the kind of piece of history hanging over his head of being the greatest ever,” she told Express Sport.
“So he’s played the majority of his career knowing that he is possibly going to end his career as the greatest ever player to have ever played.
“But of course with Nadal lurking not too far behind and Nadal being that much younger, if he decides to hang up his racket then he knows that Nadal will be reinvigorated and just continue to fight and chase the titles and he won’t be able to get that time back.
“It’s like when Sampras went, he probably never thought in a million years that in the next generation a young lad would come along and overtake his record, because at the time when he did it, it was unthinkable that someone could win 14 Grand Slams and not only did Federer do it, but he surpassed it.”
Federer is already regarded as one of the greatest players of all time but Croft thinks he wants the legacy of most Slam wins, and to set the bar so high it can’t be caught.
“I definitely think he’s after the legacy,” she added.
“That will keep him going until his body can’t continue because he’s got to stave off Nadal and that’s what keeps it exciting for the pundits and fans because it’s another subplot, not only is it special to see them play but we don’t know how long they’re going to be around so there is that subplot going on in the background and it is an amazing, amazing era in tennis.
“It’s been such a privilege to cover the sport in this era because it’s just amazing. Normally you can see we’ve had one great icon in this era, but we’ve got two up against each other and also add into that Djokovic who’s not that far behind. It’s been an amazing time to cover the sport.”
Federer goes into the Australian Open as favourite having won it last year and with his top rivals Nadal and Djokovic struggling with injury and Andy Murray already having pulled out.
Croft is backing Federer to seal his 20th win and thinks he finished last year with some of his best ever tennis.
“I think he’s playing the best tennis we’ve ever ever seen him play,” she said.
“And his movement for someone of his age, I reckon he’s moving better than we’ve ever seen him.
“He’s playing with such freedom and so much choice and what he’s does with opponents is he comes at them so fast and furious, he doesn’t give them time to think and it’s such beautiful tennis to watch and he’s reinvigorated the construction of points you know the way that he’s so aggressive, up tempo, serve-volley, attack the net, finish them off, winning points quickly it’s kind of reinvigorated that style of tennis.”
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