Sabalenka has now had to save break points in back-to-back service games.

But she's one game away from the final while Pegula is serving to stay in this semi-final.

Brilliant return from Sabalenka and there's not much Pegula could do with that. She knows it as she drops her head.

The American fires into the net and Sabalenka takes the hold.

That is HUGE.

Sabalenka turns to her box in desperation then closes her eyes, regroups, takes a breath and produces a powerful return to save break point.

This time it's Pegula who airs her frustration.

The top seed again keeps her cool to move to game point but misses the drop shot. Deuce.

Tension people, tension.

Sabalenka looks in control of her service game but a bad miss at the net and a wide backhand move us to 30-30.

Oh no! Sabalenka then slams down her racquet as she double faults to have Pegula a break back point.

David Law
Commentator on BBC Radio 5 Sports Extra

Pegula will sit down trailing at the break, but she will still believe.

Pegula responds to that tricky game where she missed three break points by holding to love.

She's saying 'hello, I'm still here'.

Image source, Getty Images

Sabalenka is two games away from the final.

But Pegula is two games away from drawing level in this set.

Up for grabs.

Sabalenka saves break point again but an ambitious second serve at game point results in a double fault to take us back to deuce.

A smash volley hands her a second bite of the cherry before she takes the hold with a big serve.

Impressive stuff from the top seed.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra and BBC Sounds

Great quality on display this evening. You have to admire Sabalenka's attitude in the most pressurised situation.

What?! I thought that was out! Sabalenka's backhand paints the line and takes us to deuce but she just overcooks it on the next point and Pegula will have a third crack at break point.

What a point to save the first break point. It's cat and mouse tennis with both players running each other ragged but Sabalenka's smash volley has the last word.

Pegula is left standing and staring at Sabalenka's passing shot as the screen shows it kissed the line.

But a couple of points later it's the Belarusian standing with her cheeks puffed out as she misses the forehand for 15-30.

Some nifty net play then brings up break back points for the American.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra and BBC Sounds

Pegula just needs to hang in there with patience, keep extending the rallies as long as she can and wait for the errors to come.

Pegula keeps her cool to take a confident hold to love and remain in touching distance.

I'm not sure 'calm' is a word often associated with Sabalenka on court but she is certainly more in control.

Pegula gets lucky with a net cord that dribbles over in her favour but a couple of big serves put the game back in the Belarusian's control and she moves to take the hold.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra and BBC Sounds

Sabalenka has definitely calmed down after that first set.

Pegula needed that.

Her first serve is still somewhat lacking but she takes the hold to love and gets herself on the board, reminding Sabalenka she's not going away in this deciding set.

Annabel Croft
Former British number one on BBC Radio 5 Sports Extra and BBC Sounds

How incredible to start so fast when it's been such an edgy match. Sabalenka finding an extra gear here.

Image source, Getty Images

Sabalenka looks like she means business now.

She takes the hold to love and consolidates that break in less than two minutes.

Well that was rapid.

Sabalenka needs just five minutes to break in the opening game of this deciding set. A perfect start.