David Beckham and the Duke and Duchess of Cambridge watch Andy Murray play Vasek Pospisil at Wimbledon Centre Court

All eyes were on Britain's No 1

David Beckham and son Romeo watch Andy Murray (GETTY IMAGES)

Andy Murray was supported by the Duke and Duchess of Cambridge and British sporting stars including David Beckham in the Wimbledon quarter-finals on Wednesday.

William and Kate, who are keen tennis fans, were in the Royal Box to see Andy Murray in action against big server Vasek Pospisil.

Wimbledon officials said Beckham was not due in the Royal Box, however the 40-year-old was anticipated at the club, possibly as a guest of a player or a sponsor.

Sporting big names arriving to take seats in the Royal Box included Olympians Sir Matthew Pinsent and Paula Radcliffe.

Murray's coach Jonas Bjorkman believes the Scot is already hitting the levels needed to win more grand slams as he gets set to continue his title push, in the first match on Centre Court.

Bjorkman joined Amelie Mauresmo on Murray's backroom team in March and has helped him scale new heights, as the Briton enjoyed his best ever season on clay and is currently on a nine-match winning streak on grass.

The Duchess and Duke of Cambridge look on (GETTY IMAGES)

Pospisil has yet to win in the pair's three previous meetings and had never gone past a grand slam third round before this tournament.

It means Murray is hot favourite to reach the semi-finals where he would be two wins away from clinching his second Wimbledon title and third grand slam overall.

"Has he got more grand slams wins in him? I think he has," Bjorkman said.

"I think he's already there, he's so committed to his tennis.

"He's working so hard, extremely hard, and I'm so impressed with the work he puts in every day.

"He really knows what it takes for him to achieve his goals. I think he's already on that way up."

Pospisil, who is ranked 56th in the world, played two five-set matches on Monday, beating Viktor Troicki in the singles before later losing to Murray's brother Jamie and John Peers in the doubles tournament.

Andy Murray hopes those demanding contests will work in his favour on Wednesday but insists extra time on court can also have its advantages.

"Pospisil had a great win over Viktor Troicki in singles earlier in the day, which meant he played 10 sets on Monday," Murray told the BBC.

"I don't know if that will affect him when we play on Wednesday but, selfishly, I hope so. He's played a lot of tennis here with three five-setters.

"The plus is that on grass the matches aren't as long - a five-setter in New York takes a bit more of a toll on your body than here - but Vasek has spent quite a lot of time on the court so far and that can be mentally draining.

"He may also be a little bit fatigued, but then again he's played so much tennis that he's going to be comfortable in the conditions and in a good rhythm.

"If he is tired I'll obviously try to capitalise on that, but I won't bank on it."

Additional reporting by PA