Image source, BBC Sport

Can the Brit continue her best run at Roland Garros? She'd failed to register a win in the main draw in Paris before this year.

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Johanna Konta's Fed Cup captain Anne Keothavong says she has yet to hit her peak.

"A lot of things are coming together but she can go up a few more levels if pushed," Keothavong told BBC Sport.

"Jo has played some fantastic tennis and the best thing is she can play even better - she is still very much playing within herself."

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The only trouble for Stan Wawrinka is that his French Open win over Roger Federer is his last victory over his compatriot.

Since then Federer has reeled off six successive wins. The head-to-head is a landslide 22-3 to the world number three.

And is Wawrinka the player he once was? He underwent knee surgery after Wimbledon 2017 that threatened his career and dropped out of the top 250 before clambering back to his current ranking of 28th.

After a five-hour plus five-setter against Greek Stefanos Tsitsipas in the last round, how will his joints be feeling?

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Stan Wawrinka is the last man to beat Roger Federer at Roland Garros.

The pair met in the 2015 quarter-final with Wawrinka rattling off a straight-set victory on his way to the title.

"I have a bad memory of it," said Federer, 37, of their 2015 encounter in the French capital.

"Stan beat me in three sets with his terrible shorts! But he played really great that year."

Image source, Getty Images

On Court Suzanne Lenglen, there is a match-up as Swiss as a cuckoo clock dipped in fondue.

Roger Federer, 20-time Grand Slam champion, takes on his compatriot Stan Wawrinka.

BBC Radio 5 Live Sports Extra

Former Wimbledon quarter-finalist Daniela Hantuchova is alongside Russell Fuller and former British player Naomi Cavaday in the BBC commentary box, and you can listen to their coverage of Johanna Konta versus Sloane Stephens online by clicking the link at the top of this page.

Jonathan Jurejko
BBC Sport at Roland Garros

British number one Johanna Konta can “bother anyone on her day”, says the legendary Martina Navratilova.

Yet the 18-time Grand Slam singles champion is still backing the American.

“I would say Sloane is the favourite, she is a better clay-court player, already a Grand Slam winner," Navratilova told reporters at a Roland Garros 'Legends' event.

“But Jo has a big serve and big shots both sides, and she is using the drop shot more which should be effective because as fast as Sloane is, she stands far behind the baseline.

“Jo can’t wait too long in a point but at the same time she can’t pull the trigger too early. She needs to pick the right moment to go for it.”

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Sloane Stephens is also confident the Roland Garros clay will level the playing field in her quarter-final meeting with Johanna Konta.

"Clay is a neutraliser. It's good for everybody... she's improved her results on clay, so she obviously is feeling good on the surface," said the American.

"A quarter-final of a slam is definitely a neutraliser. There's a lot of factors that go into that.

"(I'm) just going to go out and execute and I'm sure she'll do the same and we'll have a good match.

"She has a good, all-around solid game. I mean, obviously she's been at the top of the game before, so she knows how to play in key moments."

British number one Johanna Konta has already beaten Sloane Stephens on two occasions this year - in the Italian Open second round and in straight sets on the hard court at the Brisbane International in January.

Stephens says those two defeats will have no bearing on the encounter in Paris, insisting she will go in with "a clean slate".

"When I played her in Brisbane it was the first match of the year, so that's totally out of my mind," said Stephens, who lost to Halep in last year's final.

"And then the one in Rome, bad circumstances. Out of the mind."

Our tennis correspondent channels his inner Carol Kirkwood...

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Sloane Stephens is one of only three top-10 seeded players left in the women's draw, along with Romania's defending champion Simona Halep and Australian eighth seed Ashleigh Barty.

Konta and Barty are among five players in the Roland Garros quarter-finals for the first time, along with 17-year-old American Amanda Anisimova, Croatian 31st seed Petra Martic and Czech teenager Marketa Vondrousova

"Any one of these players still left in the draw has a good shot at it," Fed Cup captain Anne Keothavong told BBC Radio 5 live.

"Johanna Konta is playing with confidence and it has been building over the last few weeks.

"She has performed very well and this has been her best season by a country mile on clay.

"With each match she is looking more and more comfortable."

Jonathan Jurejko
BBC Sport at Roland Garros

Image source, BBC Sport

This was the scene on Chatrier a short time ago, shortly after the Roland Garros groundstaff had sweeped the court with their nets.

Pristine.

And, you'll notice, clear bright skies. For now at least...

British number one Johanna Konta says there has been a belief in the women's game that anybody is beatable for "quite some time now".

"It's nice for people to also enjoy matches where nothing's a given and it can be unpredictable," said Konta.

"That's the beauty of sport, to have battles where you're not sure what the end result is going to be until it happens."

Asked if there was a feeling everyone was beatable, she replied: "I think that's been the growing mood for quite some time now."

So what else was going on in the world 36 years ago, I hear you ask?

Irene Cara's 'Flashdance... What a Feeling' was number one in the UK charts, although it would soon be ousted by The Police hit 'Every Breath You Take'.

BBC One broadcast the first episode of Blackadder, ITV launched a new children's section and the first CDs went on sale... remember those, kids?!

Manchester United had just beaten Brighton at Wembley to win the FA Cup - the glory days, eh United fans - while middle-distance runner Steve Cram would win Sports Personality of the Year.

Oh, and Chris Evert beat Mima Jausovec - who toppled Durie in the semi-finals - to win the French Open title.

Image source, Getty Images

Should Johanna Konta win today she will become the first British woman to reach the French Open semi-finals in 36 years.

Remember the last player to make it that far? It was Jo Durie in 1983...

Jonathan Jurejko
BBC Sport at Roland Garros

While our focus might be on Jo Konta, the official Roland Garros daily newspaper has decided to go with a three-way split pic on its front page...

Turns out there are some big matches in the men's draw too.

Image source, BBC Sport

Image source, Getty Images

There is also a cracker of a men's quarter final taking place from 13:00 BST, as 20-time Grand Slam champion Roger Federer fellow Swiss and 2015 champion Stan Wawrinka.

We'll be keeping you right up to date with that one.

Johanna Konta saw off Germany's Antonia Lottner in straight sets, before beating Lauren Davis, Viktoria Kuzmova and Donna Vekic to reach this stage.

Sloane Stephens overcame Misaki Doi in the opening round and then knocked out Sara Sorribes Tormo, Polona Hercog and Garbine Muguruza to make the last eight.

Jonathan Jurejko
BBC Sport at Roland Garros

One of these names will be handwritten onto the Roland Garros draw board, nestled in a quiet corner in the shadow of the new Chatrier, again later today.

In the semi-finals section.

Croatian 31st seed Petra Martic or Czech teenager Marketa Vondrousova, playing second on Lenglen, will meet either Konta or Stephens.

Image source, BBC Sport

Image source, Reuters

Johanna Konta had never won a match in the main draw at the French Open, until this year...

Now, after four successive victories at Roland Garros, the British number one is about to face last year's runner-up Sloane Stephens in the quarter-finals.

Excited much?