Image source, AFP

Right now, it is Rafael Nadal that is having the trouble keeping hold of his serve. At 15-30, he asks Kyrgios to go wide, but another great return gives Kyrgios a second break point. Nadal digs in to his box of tricks to save, then, as if to punish Kyrgios for his insolence, has the Aussie scampering all over the baseline. An eventual hold, but Nadal is the man under pressure.

GC Nutrition:, external If Kyrgios can get that serve and forehand firing then Nadal is in for a tough afternoon!

This is unbelievable. Rafael Nadal not only can't get a racquet on the Kyrgios serve, he isn't even close to returning. Kyrgios is back on his seat pretty much by the time Nadal has given the balls back to the ball kids, hammering down the bullets at 133mph.

Oh, Nick Kyrgios, I suspect you'll have to take chances like this if you are to beat the world number one. Court open, but a backhand pushed wide as Nadal desperately scampers across the dusty ground. From there, Kyrgios doesn't get another sniff.

Nadal serving in bright sunshine, up against what is rapidly looking like a formidable opponent. A Nadal long forehand puts Kyrgios 0-30 up, the first time in the match either serve has been pressured. Nadal fights back, but another wayward forehand gives the Australian break point...

Earlier we asked you which of the new crop of women's players will win the most Grand Slams?

More than half of you (55%) think Eugenie Bouchard is a potential champion, with 22% predicting a bright future for Simona Halep and 9% of you touting Laura Robson to win a major title at some point.

Looks like Eugenie's pleased with the result...

Image source, AP

At this rate, Rafael Nadal is going to need a helmet and some body armour. Nick Kyrgios is battering down these serves, with two more aces sending him on the way to a blink-and-you'll-miss-it hold. Toss ball, arc back, jack-knife forward, watch the ball not come back. Nadal will surely be the master if he can get the ball back in play, but...

Nadal will be looking to engage the youngster in his trademark energy sapping rallys when receiving, but for now he has as serve to hold. A slight mixed bag - a first ace and a double fault - but an unstoppable double-hander down the line wraps it up.

Image source, Getty Images

Milos Raonic has edged ahead in the battle between the Next Big Things out on court four.

The Canadian leads Japanese world number 12 Kei Nishikori two sets to one after blasting through the tie-break.

If Nick Kyrgios is nervous, he's doing a good job of hiding it. Though Nadal makes his first impression on the Aussie serve, three more aces, the second his biggest serve of the Championships so far, take Kyrgios to a swift hold. That's five aces in his first two service games. Intriguing start.

Nadal is in to his deliberate routine. Bounce the ball, fiddle with the shorts, bounce, set, serve. Kyrgios is covering the ground well, punishing the ball, but the control isn't there. Long and then into the net, Nadal holds to love. No points against the serve yet.

Laura Robson
Injured British number two on BBC Radio 5 live

Laura Robson:, external SUCH a great match from Kerber and Sharapova. Amazing tennis.

The lanky Kyrgios, who could have had a career in basketball, has already found his range with the missiles. Two aces, the second of which was a bomb of a second serve. Nadal slicing and dicing, but long to give Kyrgios a hold to love. Impressive start from the Aussie.

Image source, Getty Images

Lucie Safarova on reaching her first Grand Slam semi-final: "It is amazing. I played really well and wanted to get through this match and I am so happy.

"I was serving well and being aggressive and taking her time away and that was the key to the victory."

Nadal, the champion in 2008 and 2010, is all business. White headband, muscles bursting his T-shirt, he goes through his prep as if no one is watching. The world number one has won the toss and has elected to receive. Applause as he sprints from his chair, towels placed on both sides of the court. Ready? Play.

On Angelique Kerber's win over Maria Sharapova on Centre Court:

Hazel Allen:, external That was an AWESOME tennis match!

Paul Wallis:, external Absolutely top quality tennis as Kerber beats Sharapova. A pleasure to watch.

Mike Willis:, external Wow. Gutsy for Maria to save as many match points as she did. Even more gutsy from Kerber to not implode after so many missed chances!

Tracy Austin
Two-time Grand Slam champion on BBC TV

"The crowd were on their feet afterwards because I think they saw how important that win was to Safarova. To make her first semi-final means the world to her. She puts in a lot of work and has done since she first came on the tour around a decade ago. This is the biggest moment of her career but she handled the situation better and served extremely well and played a great match."

Lucie Safarova will play the winner of the quarter-final between her fellow Czechs Petra Kvitova and Barbora Zahlavova Strycova in the last four.

The players are already out on court, knocking up. Kyrgios, the 19-year-old world number 144, arrived wearing a set of luminous pink headphones, then sat back in his chair as if he was having a pint in his back garden. Does he know where he is? The Royal Box is over there. Show some respect young man. Also, do those headphones adhere to the dress code? White only, please.

Image source, Getty Images

Angelique Kerber looks back on digging deep to beat Maria Sharapova, and facing Eugenie Bouchard in the quarter-finals:

"When I had three match points in a row I just tried to focus, believe in my game, be aggressive and it worked!

"I will focus on my next round, I lost to Genie in Paris, so I'll try to be aggressive, play my game and enjoy every single moment."

Indeed. How do we follow one of the matches of the tournament? With the chance of one of the biggest upsets since, erm, Rafael Nadal last lost at Wimbledon.

Is it it likely that Nick Kyrgios will deny Nadal his first quarter-final since 2011? No. Is it possible? Let's just see.