A second-serve ace from Madison Keys who locates the sickly sweet part of the strings to rack up another love hold.

If there is to be a dramatic shift in the direction of this match - ala Stephens v Venus - then we will have to wait a little longer.

Who stole Coco Vandeweghe's mojo?

Madison Keys is playing pretty much flawless tennis, but normally there is more pep to her New York opponent than in an entire cheerleading squad.

Keys moves to 0-30.

Vandeweghe finds a bit of momentum to drag it back to 30-30 and glimpses safety as Keys overcooks a pass.

Another slightly clumsy groundstroke from Madison Keys and Coco is a go-go in the second set.

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Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

That's really good play from Madison. Coco was a little nervous and flat at the beginning, the last few points she played were a little better.

Coco will start making a little more of a push and start mixing up her serve, throw in a few serve and volleys, put a little more pressure on Madison.

Keys came out more calm, more confident than Vandeweghe. Keys has been handling the situation better.

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Madison Keys steamrollers her way to 40-0.

A slight speed bump as Coco Vandeweghe runs around a forehand and crashes across court. She has not been given the platform to do that much so far tonight.

Another little hold-up as Keys misses her mark down the line.

But the third and final set point of the game is the charm.

Set bagged in 23 minutes.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

The second set will definitely be more of a contest. You get the sense Vandeweghe is struggling with nerves a bit. We're not seeing anything from her right now.

I thought we would see a reaction or first pump from Vandeweghe, but she's looking more tense than normal.

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That was absolutely sublime from Madison Keys as a sliced squash shot pass makes a heck of a lot more sense on court than it does typed on the screen, setting up set point.

Keys attacks the net in pursuit of the quick kill. No cigar. Volley into the net.

Vandeweghe with game point now. And she gets on the board as Keys' return gets off the leash and floats long.

Coco Vandeweghe has changed tack dramatically.

She is charging in behind her serve to try and dominate the net and sow some doubt in Keys mind.

But Vandeweghe looks like the one wrestling with demons as she double faults to 30-30.

Another error from Coco and we are into deuce.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

Keys hasn't given Coco any sort of opening. She's serving well, hitting big off the baseline. She hasn't given Coco any look to be aggressive or change the dynamic of these points.

Coco is on the defence all the time.

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Maidson Keys is carving up Coco Vandeweghe like the elephant's leg in your local doner establishment.

Absolutely ruthless and Coco absolutely outclassed.

Only 13 minutes on the clock and Madison Keys has won 20 points to Vandeweghe's four.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

You get the sense Keys is anticipating the serve much better than Coco. She understands where Coco is going to go.

Coco is struggling with Madison's serve a little more. Coco's demeanour is not the best. She usually has a lot more fire.

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This isn't one-way traffic, it is an autobahn of points flowing into Madison Keys' side of the scoreboard.

The younger woman jumps to 0-30 with an easy backhand into the unguarded court.

And then 15-40 as Vandeweghe fluffs into the net. Two break points.

She only needs one

A return right up onto Coco's toes and that is the double break.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

I don't think Coco has necessarily done anything wrong. I just think Keys is firing on all cylinders right now.

Madison is really fired up to go.

Madison Keys heads for the change-over with a break in her back pocket and two holds to love.

That is pretty much a royal flush over the first three games.

The last thing she will have wanted is a 90-second sit-down.

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Piers Newbery
BBC Sport at Flushing Meadows

Venus Williams made her way pretty much straight from the court, down the lengthy corridor and into Interview Room One. That usually signals a player in a thunderously bad mood, understandably, but Williams is already impressively measured about her night.

Asked about that dreadful start, she says: "I just wasn't playing well. Those are moments where you have to dig deep and figure out how to get the ball on the court and have a big game. I can't be tentative and try to figure out how to put that ball in.

"I figured out a lot, but she played great defence."

And the perennial question for the 37-year-old, what lies ahead?

"I will continue to play tennis. It's nothing complicated."

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

Madison was not only sharper but more aggressive off the ground. Mentally she knew she had to get that early break.

Coco took a little bit off her serve.

Madison Keys draws the first blood as Coco Vandeweghe whales a forehand into the top of the net.

She will know if she was watching the first semi-final that there is still a long, long way to go.

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Madison Keys steps in a wallops a second-serve return down the line and out of the reach of Coco Vandeweghe for 15-30.

A wicked pass, fizzing with spin, full of vicious intent, sets up two break points for Keys at 15-40.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

I didn't see any nerves from Madison Keys in that first game, but it does help when you have that big serve to back you up.

Coco has one of the best second serves in the game, she'll try to throw in some kick second serves to throw Madison off guard.

Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra

I don't think it's rocket science. It's who can hold serve and who can get that first strike on the forehands.

Madison Keys is sporting a grey/black number and that opening game could not have been more business-like if she was accessorising with a bowler hat.

A hold to love characterised by some spicy serving and sealed with a mammoth cross-court forehand hand that kicks away for a clean winner.