Novak Djokovic refused to reveal details of his chat with Queen Camilla at Wimbledon on Wednesday but admitted he was "surprised" by a question she asked him. Djokovic secured his spot in a 14th semi-final at his favourite Grand Slam, where he is a seven-time champion, by seeing off the challenge of young Italian Flavio Cobolli on Centre Court.

Djokovic came through 6-7, 7-2, 7-5, 6-4 to book a final-four showdown with world No.1 Jannik Sinner on Friday. And hours before his match, Djokovic shook hands with the Queen as she arrived to watch the action from the Royal Box.

The Serb thanked the tennis-loving Queen, accompanied by her sister Annabel Elliot, for attending the Championships. But the 24-time Grand Slam winner opted against leaking any more details of their conversation in his post-match press conference after beating Cobolli to reach the semis at the All England Club for a fifth successive year.

Reminded that he always wins when the Queen visits Wimbledon and asked what they spoke about, Djokovic said: "I prefer not sharing that. It's private. We had a nice exchange. I was actually surprised with her comment and a question that she asked. It was non-tennis related. She was very pleasant. Very, very pleasant.

"Of course, it's a great honor and privilege for me to be able to shake hands with Queen of England. I've had that honor, as well, 2010 with the late Queen Elizabeth.

"It's obviously a phenomenal occasion for Wimbledon to host the Royal Family. Wimbledon has been traditionally attracting Royal Family. It's beautiful to see there's still an interest for our sport. Of course, it's important for all of us."

Djokovic saw off Cobolli despite losing the opening set in a tiebreak and confessed he was also surprised by the Italian's level, especially on serve, in his maiden Grand Slam quarter-final. The 38-year-old added: "It was a very good battle. Credit to him for playing very well for I think entire match and serving great.

"He did surprise me. I didn't expect him to serve that well. At some parts of the match just serving so good that I wasn't to kind of read his serve or attack his serve. Just huge improvement from him I think in the last six months since the last time I faced him in Shanghai.

"Well, the results are showing his improvement. He's in quarters of the Grand Slam for the first time. I told him at the net to keep going. Bright future is ahead of him for sure if he keeps going this way."