Nick Kyrgios' former coach, Joshua Eagle, has spoken about the "extraordinary" skill and talent, but also admitted that he is uncoachable.
The Australian does not have to even turn up to play a semi-final on Friday at the All England Club after Nadal was forced to withdraw from the tournament on Thursday evening due to an abdominal tear.
For Kyrgios, it has been an incredible run on the famous grass courts, and he now awaits the winner of top seed and reigning champion Novak Djokovic's clash with Britain's Cameron Norrie on Centre Court.
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Eagle, who used to coach his fellow Australian, has given Eurosport a fascinating insight into what it is really like to work with the 27-year-old - albeit he has recognised that his former charge has made significant strides since they shared the practice courts.
“Every day is a different day with Nick," Eagle said. "You never know what you’re going to get. There’s sheer brilliance, and then absolute disappointment at other times, but that’s why people come to watch him because he’s a box of chocolates… you never know what you’re going to get.
"It’s very challenging, but I’m just pleased to see him playing at his full potential because we all know that he’s one of the great talents that the game has really ever seen.
“I don’t think anyone can [read Nick’s mind]. He marches to the beat of his own drum. It depends on how he feels on the day. At this time at Wimbledon, he seems more purposeful in what he’s doing.

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"He’s fitter, moving better, hitting the ball really well. He didn’t play on the clay so he’s tried to target the grass. Wimbledon is the Slam that he believes he can probably win.
“People either love or hate [his antics]. Tennis purists probably don’t like it, and the young generation absolutely love it. For me, sometimes it’s way over the top and I wish that he would just get on and play because I’ve worked with him one on one.
"I’ve seen the talent, I know what he’s capable of. I would love to see him fulfil that talent. I think he could have won three, four, five Slams by now, that’s how talented he is. If he could drop the antics a little bit and focus on what he does well - playing tennis - he can win these titles.
“I admire his skill level. People understand his tennis IQ: he can break down an opponent very quickly. We’ve seen him do that [here]. His tennis IQ is something that he doesn’t get credit for. His skill level is extraordinary.
“I don’t think he is coachable. He’s too far down the track in doing [things] his own way. He wouldn’t listen to anyone. He didn’t listen to me, and he wouldn’t listen to anyone! I think he’s best off doing what he does.
“He’s always wanted to play on the big courts and he really believes that’s where he belongs. He’s got the best serve in the game, as far as I’m concerned.
“He’s a polarising character [to Australians]. Half of the country would be cheering for him, the other half would be switching off. It’s a big story, and if he can channel what he’s doing, and win… then the fans might begin to like him a bit more.”
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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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