Good response. Ace out wide from Maya Joyce.

Oh no! Double fault.

Maya Joint trails 0-15 and 15-30 before pulling out a pinpoint ace down the T.

Serena Williams nets a backhand return. Match point on Centre Court.

Tracy Austin
Two-time Grand Slam champion on BBC One

If you're Serena Williams right now, the goal is to get as many returns back in play as possible to make Maya Joint feel this moment.

She has to make her earn it.

As Serena Williams struggles for energy, Maya Joint flexes hers, rushing the net and nailing a forehand volley, one foot crossed behind other.

But Williams holds to 30. Over to you, Maya - can you serve it out?

For the fourth time in this match, Stan Wawrinka and Matteo Berrettini can't be separated after 12 games and so into another tie-break we go.

Berrettini has won the past two tie-breaks and will be through if he wins this race to seven points.

Image source, Getty Images

John McEnroe
Three-time Wimbledon singles champion on BBC One

There is rather stunned silence here in not only the commentary booth but also in the crowd.

There was that easy backhand to go up 3-1 which was missed, but we all remembered it is Serena Williams. But then you remember she is 44 years old and it has been two hours and 15 minutes of play.

It is hard to digest and comprehend what's happening because it does look like all of a sudden her energy levels have dropped completely.

Image source, Getty Images

Maya Joint double faults for 40-30 but keeps her cool, even after missing another first serve, to move to within one match of the second round.

Serena Williams netted a tired backhand on game point.

Laura Robson
Former British number one on BBC One

From about halfway through the second set, I could see Serena Williams' fitness trainer telling her to eat something. She is being told to keep nibbling on the change of ends.

I think they were worried about her energy levels around half an hour ago because this is a real pick up in intensity.

Tracy Austin
Two-time Grand Slam champion on BBC One

Serena Williams seems to have lost a little energy of late. She isn't pushing up on her serve at all really.

It is like all the air has come out of the balloon on her side.

Image source, Getty Images

Annabel Croft
Former British number one on BBC Radio 5 Live

Serena Willams has gone away from slicing and odd drop shot, messing up the rhythm; they have once again gone back to this 'ding dong' battle at the baseline.

It feels like Maya Joint is finding her rhythm once again.

A limp backhand dribbles into the net. Serena Williams has gone flat.

Image source, Getty Images

Lovely from Maya Joint, opening up the court and converting a down-the-line backhand. Serena Williams was stranded. 0-30.

A double fault. Is the tide turning?

John McEnroe
Three-time Wimbledon singles champion on BBC One

You've got to love the fight from Maya Joint though because it was all coming down on her shoulders given the chances she had.

All you can ask for as a competitor is for her to keep battling. I love to see that from her.

Nick Mullins
Tennis commentator on BBC One

The 20-year-old Australian, who continues to impress us and frustrate Serena Williams, is back in front in this third set.

Maya Joint holds to 15. For the first time in this deciding set, she doesn't face any break points or have to navigate deuce.

Image source, Getty Images

Tracy Austin
Two-time Grand Slam champion on BBC One

That's a tough game for Serena Williams to lose because she was up 2-1 with the break and she added that short backhand approach that normally would've won the point.

She could've been up 3-1 there.

Maya Joint's moon-ball mis-hit clips the baseline. An immediate break back for the Australian.

Her mum applauds