or should that be Johanna Konta breaks herself.

A runt of a service game from the British number one just when the opening set is getting to its pointy end.

Sevastova will serve for the set next.

Anastasija Sevastova is tighter strung than her racquet head.

Every point won is met with a grimace and grit of the teeth. 

Every one lost is met with a string of angry Latvian and dagger looks into the stands at her box.

Her mood darkens like a tropical storm as she is pegged back from 40-0 to deuce, but Konta bops a backhand wide to fold out of the game and keep her opponent from full implosion.

Image source, EPA

Anastasija Sevastova is suffering a little out there.

The Latvian seems to have suffered a tweak somewhere in her lower half that is restricting her movement.

There are a few pointed looks from her over towards her box as Johanna Konta restores scoreboard parity.

Image source, EPA

Those three break points that Anastasija Sevastova squandered in the fourth game are only rising in value on the first-set stock exchange.

Johanna Konta carries the momentum from that salvage job into the next game and rolls over Sevastova's tee-off to put us back on serve.

The wind is behind the Briton.

Image source, Reuters

Johana Konta completes her escape and spits a pumped-up shout of "C'mon" down the other end.

That is a little spice for the stew that Anastasija Sevastova is in after missing three break points.

Konta is late to the party, but, just a break, has enough time to turn around the tanker of this first set.

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Well, well, well.

Anastasija Sevastova is chopping and slicing for all she is worth and the change of rhythm is causing a glitch in Johanna Konta's game.

The British number one is 0-40 adrift and has three double-break points to defend.

Konta slips her shackles via a delicious measured dropper and a Sevastova cross-court pass that fails to dip as its owner would like.

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Anastasija Sevastova is making herself very at home on Flushing Meadows' front room.

A crackerjack inside-out forehand skids away for a clean winner that Johanna Konta watches with her eyes, but does not bother to move any other muscles for.

That is the game to 30 and the Latvian clenches her fist towards her players' box.

Image source, AP

Johanna Konta's pre-serve routine involves a big exaggerated ball bounce. Very showy. Whatever gets you in the zone.

She does not seem to be quite in the groove though.

She dumps a forehand long as Anastasija Sevastova calls her into the net with a snake of a drop-shot to offer up two break points at 15-40.

Sevastova converts the first.

If you are going to drop serve, this is the end of the match to do so.

Image source, Getty Images

Anastasija Sevastova is in trouble at love thirty adrift, but he shapes up sharpish to see her way through.

Johanna Konta plonks long over the back to let her off the hook.

It is hardly a cauldron of atmosphere on Arthur Ashe. Attendance for the first match of the day is patchy and the new roof means that half the court is in shadow, the other in bright sunshine.

Image source, Getty Images

A peach of a day in New York - twenty three degrees, the hot dog stands just warming up to for lunch.

You can listen to this one live at the top of this page, with Russell Fuller calling the shots on BBC Radio 5 live sports extra.

Anastasija Sevastova to serve.

Image source, AP

Johanna Konta has just made her way to the main stage, closely followed by Anastasija Sevastova.

What do we know about the vowel-hungry Latvian standing in Konta's way today?

Well, she disposed of third seed Garbine Muguruza in the second round to make the rest of the draw sit up and take note.

Her run into Flushing Meadows gave little sign of that unset however. She lost in the second round at New Haven and in qualifying in Cincinnati.

She has never been beyond the last 16 at a Grand Slam.

The 25-year-old's rise and rise over the last 18 months has been the unexpected sleeper hit in British tennis' recent revival.

Should she negotiate today's meeting with Latvian world number 48 Anastasija Sevastova then she will be into a last eight meeting with either home-crowd favourite Madison Keys or former world number one Caroline Wozniacki.

Both of those stink of night-session drama.

Image source, Rex Features

Two years ago at the US Open, Johanna Konta bowed out with barely a whimper, going down in straight sets to world number 155 Shahar Peer.

Just twelve months ago at Flushing Meadows, she had to make her way through three rounds of qualifying to make the main draw.

In 2016, she is the 13th seed and opening up play on Arthur Ashe on the middle Sunday. 

And frankly it would have been a disappointment had she done anything less.