'Impossible not to say Roge Federer is the GOAT' - Mouratoglou

Federer, who is fresh off securing a third Hopman Cup title for Switzerland, is eyeing a sixth Australian Open crown in Melbourne this month.

The 36-year-old enjoyed a stunning resurgence in 2017, claiming victories at the Australian Open and Wimbledon after an enforced time away from the game.

Ahead of the first Slam of 2018, Serena Williams' coach Mouratoglou believes there is simply no longer any doubt as to who is the greatest male tennis player of all time.

"It’s impossible for me not to say Roger [is the greatest of all time] because he plays the best that anyone has played tennis and he is still winning," Mouratoglou, founder of the famous tennis academy which bears his name, exclusively told Eurosport.

"Since Roger took a few months off and came back to that level, I think players are less afraid to say when they are injured, ‘okay, I’ll stop for a few months, I’ll get ready and I’ll get healthy and it will be fine’.

"In the past, players were thinking, ‘if I stop for a few months, I will never make it back’ so they were refusing to stop and were getting injured. Players look up to people who are successful, which is normal.

"Roger was not afraid to think, ‘okay, I want to play a few more years, I’m not young and my body cannot afford to do the same as when I was 20-25, so let’s be smart and let’s play less, let’s get ready for the main events, the Grand Slams, because now for him it’s all about winning Grand Slams. Let’s build the schedule, the yearly schedule, around those four events that are the highlights of my year. Roger did that very well this year [2017].

"He accepted that he would not play at Roland Garros in order to win Wimbledon, because he thought Wimbledon is the Grand Slam, after Australia, which he won, that he had the best chance to win.

"He didn’t want to take the risk of not winning Wimbledon because of playing Roland Garros and getting injured. Clay is very demanding and he could be very tired, so he focused on Wimbledon instead. It worked, he won it. He won two Grand Slams this year, after six months of not playing on Tour.

"I think he showed that he could be out for six months - even though he is not just anyone, he is not a normal player - and come back and win more than ever. He has opened a lot of doors for other players by doing that."

Unfortunately Serena, who Mouratoglou labels the greatest female player of all time without any hesitation, had to withdraw from the Australian Open

Serena beat sister Venus in the 2017 final in Melbourne, and later revealed that she was pregnant while competing in the tournament.

The 36-year-old gave birth to daughter Alexis Olympia in September, and returned to the court in an exhibition match against Jelena Ostapenko in Abu Dhabi at the end of December.

In a statement on Snapchat, she wrote: "After performing in my first match after giving birth I realised that although I am super close I'm not where I personally want to be."

She added: "My coach [Mouratoglou] and team always said ‘only go to tournaments when you are prepared to go all the way’. I can compete – but I don’t want to just compete, I want to do far better than that and to do so, I will need a little more time.

"With that being said, and even though I am disappointed about it, I’ve decided not to compete in the Australian Open this year.

"The memory of last year’s Open is one that I will carry with me, and Olympia and I look forward to coming back again. I appreciate the support and understanding of my fans and everyone at the Australian Open."