There is not even a suggestion of wobble, waver or quiver in Jennifer Brady's game so far.

Naomi Osaka asks the question and she provides the answer eloquently and bluntly enough. She shuts the door and we stay on serve.

Russell Fuller
BBC tennis correspondent

It's breathtaking stuff. There would have been a lot of sharp intakes of breaths on Arthur Ashe Stadium if there had been a crowd here.

Short is sweet for Jennifer Brady. The American is not interested in a game of tennis breaking out. Instead she is crushing the ball early in the rallies to try and snuff out Osaka's hopes.

Osaka has a bit more street-smarts when the exchanges do go longer, edging her way to 40-30 via a skidding backhand slice.

Brady on the run and into the net. Deuce.

Break-point Brady.

But the American misses the return! That was a chance wasted.

And Naomi Osaka makes sure she is not offered another.

Will that boomerang back on Brady? So often a missed break chance is followed by a faltering serve...

Now then. Naomi Osaka looks on the charge at 40-0 up, but Jennifer Brady puts a spanner in the spokes, Osaka flops a forehand and we have our first slice of deuce pie.

Russell Fuller
BBC tennis correspondent

It's quite spectacular hard-hitting we are watching in the first few games of the match,

Jennifer Brady looks really comfortable, absolutely belting the ball.

Naomi Osaka unleashes a stinging inside-out forehand that stretches Jennifer Brady all out of shape.

40-30 and maybe Osaka can drag Brady down to deuce-town for a duke-out?

Or maybe not. Brady uncorks a popping ace that singes the nostril hair as it rears up off a length.

Game. Not even a break point yet, never mind a break.

Image source, EPA

I hope you have your cocoa, caffeine or carafe of red. Whatever helps you go the long haul because this match looks like it might go deep towards the BST dawn.

Naomi Osaka, just like Brady on the opposite side of the net, has started at a canter. Both serves are solid as Fort Knox so far.

Jennifer Brady looks to be in bit of a hole as a double faults sees her slide to 0-30 down.

When you have the dynamite she has, you can make a tight hole into a crater pretty quick.

Mammoth hitting, jumbo groundies and she has salvaged the game.

Honestly, I might start a charity appeal for the balls. Absolute brutality out there...

The ball is being pummelled like a punchbag. Vicious hitting from the baseline as both players rev it to the red and attempt to blow the opposition off the court and out of sight.

So far neither has blinked in this stand-off. Osaka holds serve. Time for a sit on the stool and a slab of dance musak.

Image source, EPA

Gigi Salmon
BBC Radio 5 Live Sports Extra tennis commentator

You can't see any nerves with Jennifer Brady, if she has got any she's disguising them really well. She's looking really loose and easy.

Naomi Osaka gets a little toehold in the game as she forces Jennifer Brady wide for 15-15.

Osaka misses a second-serve return, but then comes out on top in a wham-bam baseline exchange for a look at 30-all.

Brady comes into the net behind some bruising groundstrokes and clambers into a high forehand bounce like she is wearing crampons.

She hit that so hard she snapped her shoelaces. A quick pause. A rethread and she is back to polish off the game. Impressive hold.

Naomi Osaka is not bothering with any looseners. The sound of her serve walloping off the centre of the strings cannons around the empty Arthur Ashe arena.

Jennifer Brady is struggling to get a handle on it or a return in play.

When she does, at 40-0 down, Osaka cracks away a winning cross-court forehand on the third shot of the rally.

Ominious.

Naomi Osaka won the toss and has the fuzz in her paw.

First service game incoming...

Naomi Osaka, speaking in her on-court interview: "I think naturally I've been fortunate to play a lot of matches here so that has helped me out.

"All I've been focused on this tournament is having a positive attitude and for me that's my number one key to winning today's match."

Image source, EPA

Jennifer Brady, speaking in her on-court interview: "It has been spectacular, I've received so much support from family, friends, former coaches and other players. It has been overwhelming.

"I think I'm going to have to play my game, trust my game and trust myself and believe myself I can win this match."

Jennifer Brady has her poker face on. If there are any nerves as she prepares to negotiate her first Grand Slam semi-final, she isn't showing it.

She did reveal that there were some butterflies behind the facade after her win over Yulia Putintseva in the last eight however.

“Coming into the match today, honestly. I was feeling like I was going to poop my pants," she said.

We have all been there.

Naomi Osaka emerges on to court in a riot of neon, with a giant bumbag/fanny pack and her phone in her hand.

And then some pre-match soundbites.

"Matchplay has helped me out. I have been focused on having a positive attitude throughout this tournament," she tells the on-court interviewer.

David Law
BBC Radio 5 Live Sports Extra tennis commentator

It feels like we have the right set of results here - the three big names, including a blast from the past (Victoria Azarenka), plus a newcomer in Jennifer Brady.

Because of the way she has beaten people to get here Brady feels like a big name. But will she come out here and freeze?

Image source, Getty Images

Naomi Osaka doesn't do over-looked or under-the-radar.

The 22-year-old won this title in 2018 in unforgettable circumstances as Serena Williams and umpire Carlos Ramos crossed words.

Had things been another way, she might have been bearing the weight of a host nation's expectations at Tokyo 2020.

As, it is the two-time major champion and former number one just has the relative light work of the last four of Flushing Meadowns to deal with.

She has never been this deep in a Grand Slam without lifting the pot on final weekend.