Gary Rose
BBC Sport at Wimbledon

There are a few empty seats around Centre Court but this is certainly one to watch as it has the potential to get spicy.

Danielle Collins knocked Iga Swiatek out of the Italian Open earlier this year and things have been a bit frosty between the two in the past., external

No signs of any simmering tensions so far, but Swiatek is in control of this match at the moment.

Some early pressure on Emma Navarro's service game.

Barbora Krejcikova gets herself to 0-30 and a nice smash brings up three break points.

The defending champion can't take the first or the second, third time lucky?

Image source, Reuters

And there's the hold of serve.

Last chance saloon for Danielle Collins as far as this first set goes. At the very least, she'll want a comfortable service hold now to increase her confidence.

Danielle Collins walks across to the other side of the court thinking Iga Swiatek has double-faulted. It was only the first serve though, and Collins smiles with a "I can't believe I've just done that" look as she heads back to the correct side to return.

Swiatek nets a groundstroke so Collins has two break points, but the Pole finds a couple of fine serves to get it back to deuce.

It was looking like the start Barbora Krejcikova would have wanted at 40-0 up

But Emma Navarro brings herself back into it 40-15 and a double fault from the defending champion adds more pressure.

Krejcikova steadies herself, though, and gets the early hold of serve.

And after an extended break we are back under way on Court One for this intriguing third set...

Barbora Krejcikova gets us started.

Sonia Oxley
BBC Sport at Wimbledon

Krejcikova has made a swift exit from Court One after dropping that set, maybe to gather her thoughts. Navarro, meanwhile, is on her feet by the scoreboard, she doesn’t need to sit down, she’s raring to build on the momentum.

Image source, BBC Sport

Danielle Collins goes long with a forehand on break point and Iga Swiatek gets a second break of serve.

Six winners and 11 unforced errors from the American in the opening five games - she's certainly not holding back and it's virtually all or nothing when the ball is in her hitting zone.

Martina Navratilova
Nine-time Wimbledon singles champion on BBC Two

Emma Navarro did not panic. She doesn't panic, she believes in herself.

She's defending really well and she was more proactive in her shot-making.

Too many unforced errors from Barbora Krejcikova and Navarro is just letting her beat herself.

Image source, PA Media

A let cord that could have helped Barbora Krejcikova does not as she puts the ball wide at 15-30.

It is an opportunity missed for the defending champion as a deft lob followed up with a winner brings up set point for Emma Navarro.

A big return from Krejcikova saves the first, but good serving from the American brings up another chance.

Krejcikova can't save this one as her backhand goes into the net and Navarro brings this match level at one-set-a-piece.

A couple of deuces but eventually Iga Swiatek holds serve for a 3-1 lead in set one.

Sonia Oxley
BBC Sport at Wimbledon

Image source, Getty Images

This is turning into a fascinating match on Court One. Krejcikova has asked to see a few replays of the electronic calls that have gone against her in recent games - it's not going to change anything but you feel she just has to know by exactly how many fractions of a width of a blade of grass the shot was out.

It does also buy her a few seconds to compose herself at a time when it feels like the tide is turning.

Danielle Collins mis-hits a return of serve so badly that it flies straight up in the air and into the gaggle of sporting stars in the Royal Box.

From what I hear, England's bowlers could do with a few of those edges behind at Edgbaston at the moment.

Meanwhile, Collins gets her first break point of the match but a one-two punch from Iga Swiatek saves that comfortably.

Barbora Krejcikova seems to be beating herself at the moment.

Emma Navarro just needs to put the ball back in play and wait for the Czech to make a mistake.

The tactic brings up three break points for the American, but Krejcikova's fastest serve of the match saves the first one.

Another mistake as she sends a ball at the net long and Krejcikova is broken.

Navarro will serve for the set.

As both players demonstrate their power-hitting off the ground, Iga Swiatek earns two more break points.

Danielle Collins saves the first with a 113mph serve but she goes wide with a forehand from mid-court and Swiatek has the first break of the match.

Image source, Getty Images

Grigor Dimitrov and Sebastian Ofner have raced through another set on court three. This one took just 35 minutes!

The Bulgarian 19th seed has opened up a two-set advantage over Ofner, sealing the second set with a fabulous ace which the Austrian just could not control.

However, Ofner is off to a flying start in the third set. The unseeded player has nicked an early break of serve to take a 2-0 lead.

Barbora Krejcikova is handling the pace of Emma Navarro's shots well.

She puts a bit more pressure on the 17th seed's serve to get it to 30-30 but hits a wild shot that goes miles wide.

ANOTHER Navarro shot catches the line by a millimetre and she gets her hold to edge in front again.

A firm backhand winner from Danielle Collins gets the American to 30-30 in Iga Swiatek's first service game.

The Pole, seeded eighth but ranked fourth in the world, sees it out from there.

That has to be one of the closest close calls I have seen this Wimbledon.

One millimetre in for Emma Navarro's shot and she gets to 15-15 on Barbora Krejcikova's serve.

However, the defending champion finds her rhythm on her serve again and holds comfortably in the end.

We are back level in this second set.