Fantastic play at the net between the two, Andreescu goes for the drop shot but Williams hurtles towards the centre and smashes an unstoppable volley past her opponent. Big, big reaction from the crowd.

The next point she sends a perfect backhand down the line, and then an ace.

Andreescu pulls a point back but Williams holds. She's on the board and she is happy with that one. "C'MONNNN" she screams.

Naomi Broady
British player on Radio 5 Live Sports Extra

It will be interesting to see how Andreescu acts today with the crowd so heavily against her.

Jonathan Jurejko
BBC Sport at Flushing Meadows

Well, well, well. That has changed the atmosphere some what. A party vibe has been replaced by some shouts of support which feature an element of concern.

Two cracking winners from Williams to lead at 30-15.

Andreescu responds with an ace before Williams struggles to return her next serve.

The Canadian holds.

Naomi Broady
British player on Radio 5 Live Sports Extra

She's slightly too cautious and trying to be slightly too careful, and in the end, Andreescu has broken.

Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

This is huge at the beginning of the match.

Two consecutive double faults and Williams concedes her first service game.

Not the start she will have been looking for.

Image source, Getty Images

Uh oh. A double fault from Williams at deuce and Andreescu has break point.

An ace to kick us off from Williams before she skews a backhand wide.

A couple of Andreescu errors follow before more from Williams to bring up deuce.

Russell Fuller
BBC tennis correspondent at Flushing Meadows

If she serves well, it's going to be very, very difficult for Andreescu.

Serena Williams to serve first in the US Open final.

Play.

Right, warm-ups done. Arthur Ashe is packed.

It's time.

Image source, EPA

Jonathan Jurejko
BBC Sport at Flushing Meadows

If this noise doesn’t give you goosebumps then you’re not human.

Incredible roar as Serena Williams strolls out on to a almost-deafening reception from the American crowd.

Image source, BBC Sport

Naomi Broady
British player on Radio 5 Live Sports Extra

The hairband that's around Andreescu's arm is definitely a superstition. She started wearing it at the start of the year and now she's on this incredible run.

She's so confident in huge moments. She looks like she's born to be out here on the biggest stage.

Sulaimon Adelekan: Serena Williams is again inches from winning her record equalling 24th grand slam title especially last year's emotional and controversial US Open final loss to Naomi Osaka. We all hope Queen Serena can come through this time and she will.

Russell Fuller
BBC tennis correspondent at Flushing Meadows

I think there's a feeling that this might be the time that Serena wins this 24th Grand Slam title, but at the same time, a lot of people feel that Bianca Andreescu can upset Williams.

Jonathan Jurejko
BBC Sport at Flushing Meadows

Earlier there was a buzz as snappers tried to get a glimpse of Meghan Markle - Serena’s friend - coming into Ashe.

Although Williams’ player box is the opposite corner to the media seats, we’re pretty sure it is the Duchess of Sussex who is sitting behind the player’s husband Alexis.

Nothing wrong with your eyesight, JJ!

Image source, EPA

Serena Williams will turn 38 on 26 September.

Just 18 years and 263 days separate our finalists tonight. That's a record in women's Grand Slams in the Open era.

Jeff Tarango
Former professional tennis player on BBC Radio 5 live sports extra

We can compare Serena to last year, we can compare her to Wimbledon. She lost a significant amount of weight, become a lot more fit since Wimbledon. She, mentally, is hungry. She's at the top of the mountain now and she wants to strike.

Andreescu and Williams have arrived on court.

A quick warm-up and then we will be getting under way.