Eurosport's Mats Wilander and Alex Corretja have given their views on the great rivalries between Roger Federer, Rafael Nadal and Novak Djokovic.
The legendary trio all started the year on 20 Grand Slam singles titles, with Nadal having added two more to his tally at the Australian Open and French Open.
While Nadal and Djokovic are vying for another major title at Wimbledon this week, Federer is still recovering from injury and has hinted that he will have one last tilt at SW19 to come next year.
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Nadal said over the weekend that Federer has been his "greatest rival".
Wilander and Corretja have explained what has made the head-to-head matches and rivalries so special and unique over the years, with Federer and Nadal going back even further on the biggest stage.
“I think both of them have taken the game to a different level," seven-time Grand Slam champion Wilander said of Federer and Nadal.
"Without Rafa and Novak, Roger could have maybe won 30 Grand Slams, but that’s kind of irrelevant. He was pushed to a different level by those two.
"As a tennis player, you’re not going out there to win the most majors, you’re going out there to improve your game and get to a certain level.
"Why does Rafa see Roger as his greatest rival? I think it has to do with history, of course, the matches you play… but also the enjoyment factor of playing against the opponent.
"How can you not enjoy playing against Roger Federer? I think Rafa enjoyed playing Roger maybe more than Roger enjoyed playing Rafa because Rafa was the youngster, a leftie… difficult.
"The contrast of style [as well]. It’s the most interesting rivalry for me.”

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Former world No. 2 Corretja added: “Who doesn’t miss Roger? We’d all like to see him back playing.
"It’s nice from Rafa to say that because he is his big rival and he has created a lot of problems for him over the years. Both have improved their games because of each other.
"You saw last year when Roger was stepping in with his backhand because of Rafa’s forehand. Maybe, if he had never played against Rafa, he wouldn’t have tried. It’s been great for both of them.”
In a conversation on Centre Court during a walk-on for past champions on Sunday, Federer said he is still aiming to return to his favourite event.
"I’ve been lucky enough to play a lot of matches here," he said. "It feels awkward to be here in a different type of role.
"This court has given me my biggest wins and my biggest losses. I hope I can come back one more time. I miss being here.
“I didn’t think it would take this long to come back; this year has been rough on me. I didn’t know if I should make the trip, but I’m happy to be standing here today.
"2001 [stands out] against Sampras [Federer beat the American legend to end his title defence], and then in 2003, against Mark Philippoussis [to win his first title].
"You [Sue Barker, who was speaking to Federer] remember what that meant to me [the Swiss cried during his winner's speech]."
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Watch daily highlights from Wimbledon at 10pm on Eurosport 2 and discovery+ from June 27, as well as the two singles finals live on July 9 and 10.
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