Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

Oh my goodness, it had to be that good. He was clubbing the ball and hurling himself on it just to get that extra power onto it. Perfection.

That was very tentative from Zverev.

Karen Khachanov has won 13 of 14 possible points at the net. He doesn't visit often, but when he does he does it well.

And he's playing brilliantly from the back of the court too, a huge forehand strike into the back corner and he celebrates like a nonchalant gladiator to the baying crowd.

As in set two, this match has really come alive in the tie break.

Alex Zverev has allowed this set to drift into the unpredictability of a tie break, and is on the back foot as Khachanov slams a forehand winner down the line for an early mini-break.

Khachanov consolidates it with a rare visit to the net, and the crowd love that. They want this match to continue!

Alexander Zverev and Karen Khachanov are both very annoyed by the reflections caused by the opening and closing of doors in the hospitality boxes. As the sun sets, it is more likely to be accidentally reflected into their eyes. Not what you need at this crucial moment.

At 30-0, Zverev goes back to complain to the umpire, insisting that the doors should not be opened during the point. The umpire, surprisingly, declines to make an announcement to that effect.

After all that, Khachanov holds to love for the fourth time in six service games. The inevitable tie break arrives.

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What a strangely low key set this has been.

There have been only 15 winners, compared to 29 in set two.

Both men have firmly locked down their serve in this set.

Zverev holds to love. That's an 11th successive game on serve.

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

Khachanov is in lockdown mode, he is doing well with this service game and is keeping things as tight as possible.

It is very odd just how passive Alex Zverev has been receiving serve in this third set. He has stood back from the baseline and let Khachanov dominate.

Khachanov holds to 15. That's just two of 22 receiving points won by Zverev in this set.

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9 to 5 plays during the change of ends. We miss you Dolly.

Karen Khachanov serves to try to stay in the US Open.

We seem to be slowly rolling towards another tie break, until Zverev chucks in a lazy double fault. 40-30.

The German steps up to see off the danger. Can he raise his levels to win this match in the next game?

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

I think movement is the biggest difference between these two. Zverev's movement for somebody his size is incredible.

Karen Khachanov remains undaunted by the massive climb he is faced with.

Some big serving sees him hold to love. Khachanov has still only lost one point on serve in the third set.

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Zverev digs it out when needed, sealed with ace number 14 of the match.

A massive game coming up - break, and Zverev will serve for a place in the final.

There is a strange atmosphere at Flushing Meadows, with the crowd very subdued as if expecting the end soon. This is despite Karen Khachanov not noticeably dropping his level at this moment.

And he's certainly still in this game, a 99mph forehand winner taking us to deuce on the Zverev serve.

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

It has felt a bit uneventful this third set. They are just ticking along.

Karen Khachanov is continuing to serve much more consistently than Zverev, albeit he cannot produce the same power or the same number of aces.

He holds to love, he has only dropped a single point on serve in set three.

An ongoing subplot through this whole match, which we have not commented on yet, is that Alex Zverev has been complaining about the fit of his shirt throughout. It's not even that nice, kind of an off pink.

Anyway, Zverev has enough arm manoeuvrability to send down his 13th ace of the match on his way to a hold to 30.

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Annabel Croft
Former British number one on BBC Radio 5 Sports Extra 2

It does feel that Khachanov has just one way to win this match tactically and that is really hard to keep up.

See, that's why Karen Khachanov has been hitting the fur off the ball all match. A rare attempted drop shot plops in half-way up the net.

Khachanov redeems himself with a hold, sealed with his first ace of the third set.

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