The first moment of jeopardy in the deciding set as Naomi Osaka puts into the net to hand over two break points.

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No messing about from Amanda Anisimova now. She wraps up a hold to 15 with a booming ace straight down the T.

Three service holds in a row. That's a rare sight.

Arthur Ashe Stadium has emptied out a fair bit, with some fans walking out after the clock struck midnight in New York.

It hasn't been the best quality match, but surely you can't leave now!

Osaka grinds out a service hold to get herself up and running in the decider.

After a couple of nervy unforced errors, Anisimova gets back on track with that brilliant backhand of hers.

And there's a pacey serve to wrap up the hold. A solid start for the American.

Naomi Osaka is back. She ended that second set looking down and dejected - understandably so.

Let's see what she's got left in her locker.

Anisimova is first to serve in the decider.

What way is this semi-final going to go? It's impossible to tell.

Amanda Anisimova is looking rather calm as she receives instructions from her coach while waiting for Naomi Osaka to return to the court.

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Amanda Anisimova can't take the first chance but gets it at the second attempt.

We are going to a third set.

Put the kettle on for a fresh batch of coffee.

But Amanda Anisimova returns the favour.

Set points for the American.

Wow.

Naomi Osaka gambles and moves too early across the baseline as Amanda Anisimova digs out a backhand winner.

Osaka comes up with a forehand winner of her own to wipe off one of those mini-breaks.

Amanda Anisimova makes it four points in a row - she's running away with this.

Naomi Osaka manages to halt her progress but can she claw any ground back?

Amanda Anisimova follows with a couple of holds.

Naomi Osaka turns away, stares into the distance and composes herself before preparing to serve.

Amanda Anisimova folded in the first set tie-break but she's off to a perfect start here.

A mini-break for the home hope.

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We've also had just over two hours of play in this match. We could be set for another hour if Amanda Anisimova refuses to give this game up.

The American stands firm and we're on to the tie-break.

As the clock strikes midnight in New York, Naomi Osaka strikes an authoritative forehand winner to seal the hold.

Amanda Anisimova will serve to stay in the match.

Naomi Osaka gets to advantage and thinks she sealed the hold with an ace but it's called out.

A slower second serves sees her dragged into a rally and the Japanese eventually hooks into the net for second deuce.

Naomi Osaka saves the first with a winner down the line.

Amanda Anisimova goes big on her next return and it's deuce.

Maybe a frustrated Amanda Anisimova is more dangerous.

Two break point opportunities.

Amanda Anisimova's coach has just told her to "calm down" and said he's not the one she should be fighting with.

Can Naomi Osaka seize on this moment of frustration from her opponent?

Naomi Osaka tries to guide a forehand down the line but it lands the wrong side as far as she is concerned.

Amanda Anisimova double-faults and the break is handed back.

Naomi Osaka hit back with a break immediately earlier in this set and she needs to do the same again now or we're going to a third.

Osaka slams over a backhand winner for 0-30.

Amanda Anisimova puts into the net and Osaka has three break points.