Oosh! Osaka comes to the net and pulls off a lovely sliced volley. Coco mixes it up with a slice of her own but Osaka responds with a thumping backhand.

The defending champ then whips the best shot of the match so far - a backhand cross-court winner. Two break points.

Jonathan Jurejko
BBC Sport at Flushing Meadows

Rod Laver in the house!

The Australian great appears on the big screen to huge cheers - with Elton John's 'Rocketman' pumping out of the speakers.

The only choice.

Game on!

Osaka pulls a forehand into the net. Great depth from Coco's baseline returns.

Osaka gobbles up a short ball to hit her ninth winner of the match so far but drags a forehand wide.

The world number one is then caught out by a backhand return and faces two break points.

Gigi Salmon
BBC Radio 5 Live

Naomi Osaka has got off to a flyer. She took the opening three games in 11 minutes - it did lead to a silencing of the Arthur Ashe crowd, with the stadium absolutely packed to the brim.

Better from Coco, who races to 30-0 before Osaka gets on the board with a thumping overhead volley.

The teenager then drops a 105 mph ace... and follows it up with another one! "Come on," she roars.

Image source, EPA

Osaka means business. She is playing clean, aggressive tennis. Coco is trying to play the same game but hasn't quite got the power to match so far.

The Japanese drags a forehand but throws a huge second serve out wide, which Coco can only poke into the crowd. 30-15.

Osaka's brilliant forehand is cancelled out by a backhand of Coco's. But the teenager then skews one into the net.

Image source, EPA

Jonathan Jurejko
BBC Sport at Flushing Meadows

Double faults have been an issue for Gauff here, contributing to some patchy service games.

The teenager made 11 in her first match, another seven in her second. Not ideal timing for her first one of the night.

Double-fault. Ouch. Rough start for the youngster.

Coco looks in her element on this showcase court in front of her home crowd. But Osaka reminds her who she's playing with a stunning forehand down the line.

And the 15-year-old goes a break point down when her own forehand is pulled long.

As opening games go, that was very good! This is set to be a cracker.

What a start! An unreturned serve, an ace and a clean backhand winner. 40-0.

Coco comes out on top in the next rally - greeted by huge cheers - and Osaka flashes a passing shot wide. 40-30...

Ace. Game Osaka.

Off we go! World number one Osaka to kick things off.

*Denotes the server.

Jonathan Jurejko
BBC Sport at Flushing Meadows

Image source, BBC Sport

Goosebumps already. That’s just the fans. Ear-drum perforating noise as Gauff is introduced first, with the decibel meter dipping only slightly for Osaka.

Ashe loves both of these exciting talents.

Image source, BBC Sport

Home favourite Coco Gauff hopes to become the youngest player to beat a world number one since 1991.

*One minute* the umpire calls.

Osaka is warming up in a big rain jacket. How is that comfortable? She's still hitting the tennis ball better than I could ever hope to!

Jonathan Jurejko
BBC Sport at Flushing Meadows

But not everyone loitering outside Ashe has been so lucky...

This shy elderly bloke from Brooklyn (he doesn’t want to be on camera or give his name) has paid 125 bucks to come into the grounds in the hope of nabbing a last-minute seat inside Ashe.

Kudos for his ingenuity... turning a table tennis bat into a beg for a ticket.

Image source, BBC Sport

Here they come! There's a huge roar as Coco Gauff walks onto Arthur Ashe. Defending champion Naomi Osaka follows, looking a little nervous again. She got a warm welcome too though.

Image source, Reuters