• Sore hip should not prevent him defending his title at full tilt • Murray announces he and wife Kim are expecting second child

At last the sun came out for Andy Murray at Wimbledon on Sunday, a nervous smile to acknowledge the pending arrival of a second child and an expression of confidence that his sore hip should not prevent him defending his title at full tilt.

The breaking news that he and his wife, Kim, will be celebrating the birth of a brother or sister for 17-month-old Sophia in the autumn lifted what had been a considerable weight from the champion’s shoulders although, despite his protestations to the contrary, there was lingering evidence in practice on Sunday morning that his movement is not as sharp as he would like.

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Murray took a tumble reaching for a backhand during a hit with Grigor Dimitrov and his hands went to his knees more than once as he stretched his body as near to the limit as he dared just a day before he opens the tournament on Centre Court against the unpredictable young Russian Alexander Bublik.

Asked first about the more important development in his week, Murray denied the prospect of being a father for the second time would bring added stress to his fortnight. “No, I wouldn’t have thought so,” he said. “We’re both obviously very happy and looking forward to it.”

Pressed again about whether or not he could devote full focus to his tennis, he replied: “Well, I mean, I’ve had family the whole time I’ve been playing tennis, so yeah, I’ll be fine dealing with that. It’s certainly not a distraction in the slightest.”

Reluctant to go into detail about his wife’s pregnancy (which had become obvious, at least, to the phalanx of photographers snapping her at Roland Garros a month ago), he said: “She’ll be coming to Wimbledon, yeah. And we found out a while ago. But I’m not interested in discussing the dates of that in here.”

Of more immediate concern is his fitness. The world No1 has struggled all week to deflect concern about a sore hip that, it transpires, has a longer history than most observers were aware. After cancelling two exhibition matches and three days of training last week, he hit with more vigour against David Ferrer and the British players Alex Ward and Aidan McHugh on Saturday – and even jogged at decent pace later on past the media room – but looked to be creaking a little on Sunday morning.

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Murray served well and struck the ball cleanly, especially on the forehand side, but his challenge seems to be uncertainty on the backhand, his naturally strong wing. If he is vulnerable there and the rest of the field become alive to the prospect of testing any perceived weakness, he could struggle.

He insisted: “The last few days have been very good. Practice each day has got a little bit better. It’s been slightly stop-start preparations. But each day I’ve felt better. A little bit like at the French Open, where maybe I didn’t come in as well prepared [but reached the semi-finals], I still found a way with each match to feel a bit better, and built confidence each day. I’m hoping that’s the case here.”