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Kvitova digs deep and sends her left-handed forehand even deeper, that claws one set point back off Williams, but the Czech can't save another.

First set Venus.

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It's Venus Williams with the momentum. Can she turn it into a first set win?

That's wonderful, soft hands from the American. It's been all power so far but she scoops a sliding Kvitova return over the net and leaves the Czech chasing to no avail.

Two set points.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

I thought that Petra Kvitova did well in getting deep into Venus Williams' backhand, but the American has got just such a smooth, well-timed stroke she is able to hit clean winners from behind the baseline

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Kvitova hasn't quite got her eye in. She takes three attempts to find the target off her a mammoth left-hand serve and that gives Williams the half-second she needs to trouble the Czech.

Kvitova looks frustrated. Williams has three break points.

And she only needs one, without former Wimbledon champion Kvitova so much as troubling the scorers in that service game.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

The fireworks are just about to start. The two players are settling into the match with the first serves firing and slowly sussing out their opponent. The combination of a left-hander playing a right-hander needs a little to settle down.

Piers Newbery
BBC Sport at Flushing Meadows

After barely half-full stands at the start, the bulk of the night crowd are filing in at the changeovers now. With them comes an increase in volume - the couple behind me are having a loud conversation about flights to Canada - meanwhile, down in front of them the tennis has been less than spectacular. Double faults, errors, nerves - neither woman has found any rhythm yet.

Venus Williams would be some poker player. There's no reading her emotions early on in this quarter-final - a slight jig after a Kvitova forehand goes long the only indication she enjoyed that one.

The American can't find the legs to make a passing forehand though, does that give Kvitova a route back into this one? No. Williams sweeps up with forceful serve.

Image source, Reuters

That's a little wayward from Petra Kvitova as she's pinned back beyond the baseline by Venus Williams.

The American is forever swaying as she awaits Kvitova's serve and then flings one back with more spin than an *insert party of your choice here* campaign to get the Czech scrambling.

And she breaks! Game on. The crowd love that.

Russell Fuller
BBC tennis correspondent at Flushing Meadows

Image source, BBC Sport

Spectators streaming past the fountain and into Ashe stadium on a humid but breezy evening. Many loaded with food and drink and hoping for an American double.

Anything you can do... Venus Williams shows she's just as potent when the ball drops on her forehand side.

The veteran American plucks one of out the air with a volley that rips through the New York night.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Before this match, I would have said both these women are slow starters, but Petra Kvitova has come out quicker to take advantage of Venus Williams struggling to find her range.

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There's still people flooding into the Arthur Ashe Stadium. Petra Kvitova doesn't look too impressed at the hot dog-wielding fans who've turned up late. And there's an off-putting murmur sweeping around the stands as they clamber into their seats.

It doesn't seem to faze the Czech, mind. She whizzes across the blue surface in a flash of silver and grey, headband and all, to put Venus Williams away with a forceful array of backhands, complemented by a formidable serve.

Gigi Salmon
BBC Radio 5 live sports extra commentator at Flushing Meadows

Back-to-back double faults from Venus Williams to force those initial two break points and then another to seal the break.

Those mistakes come from the pressure that comes from Petra Kvitova's aggressive stance as she stands up to the American's second serve.

Venus Williams claws one of those break points back with some powerful strokes that send Petra Kvitova scrambling, but the American adds her third double fault of the game and that gives the Czech the early advantage in this quarter-final.

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Petra Kvitova challenges a long Venus Williams forehand that looked like it clipped the line... and it did.

It's Williams' turn to double fault, though, and she follows up with another to give Kvitova twobreak point chances.

That's not the start Petra Kvitova was looking for in her first service game. A disappointing double fault.

No signs of nerves from the Czech as she sends a perfectly-placed backhand beyond the reach of Venus Williams to level though.

There's been some bruising early serves from each competitor, but another double fault allows Williams back in.

Eventually, via a single deuce, Kvitova holds.

Jeff Tarango
Former professional tennis player on 5 live sports extra at Flushing Meadows

Venus Williams feels like she was born on this court, she is so comfortable out on Arthur Ashe.

Everyone has a few nerves in the first week, but once you are up and running it is a lot easier.

Image source, Getty Images

Venus Williams' second serve is really something. She fires a corker down to put the first points on the board and then races into a 40-0 lead with an untouchable ace.

Petra Kvitova flicks a left-handed forehand across court to open her book, but Venus responds with another punishing serve to hold.

We're under way. It's Venus Williams to serve first. The Arthur Ashe falls silent, almost...