Wimbledon is yet to begin but defending champion Andy Murray is already celebrating – his wife Kim is expecting their second child.

The Mail on Sunday understands that the couple, both 30, whose daughter Sophia is 17 months old, have already announced the news to family and friends.

Speculation will now mount that his wife’s pregnancy may have been affecting Murray’s performances on the court.

Although he is still world number one, he begins the defence of his Wimbledon title tomorrow with question marks hanging over his form and fitness.

Andy Murray (pictured) is thought to be expecting his second child

After Sophia was born he stressed that his family was his first priority, saying: ‘My child is more important to me and my wife is more important to me than a tennis match.

‘It’s a big change for me and my wife, but that’s the current priority.’

Having pulled out of two scheduled exhibition matches on Friday because of a niggling hip injury, he came through three hours of practice unscathed yesterday.

‘The session was good, I’m OK,’ he said afterwards.

Kim’s pregnancy was confirmed by the tennis star’s agent who said the couple did not wish to comment.

Pictured left: Kim watching Andy play in Paris last month. Right: The couple at the Wimbledon Winners Ball at The Guildhall in 2016

Earlier this month Murray revealed he missed Sophia’s first steps because he was playing overseas.

Discussing how ‘hard’ it is being abroad for tournaments during ‘major milestones’, he also suggested that he had missed Sophia’s first words.

Last December, he capped a spectacular year when he became the youngest man in living memory to be knighted after winning both the Wimbledon and Olympic titles for the second time.

Tomorrow he takes on Russian Alexander Bublik, who is 134th in the world rankings, on Centre Court.