So Saturday's final will be Serena Williams v Lucie Safarova.

Safarova will have to overturn a 8-0 losing record against Williams if she is to lay her mitts on her first Grand Slam title. But with Williams in such unpredictably out of sorts form you never know.

See you here for that and possibly the small matter of the men's semi-finals tomorrow. Ciao for now.

The drama was in the detail, but let's have a look at the stats behind that see-sawing merry-go-round of a match.

Williams-Bacsinszky

Aces: 8-4

First serve %: 57-70

Double faults: 0-3

% pts won on first serve: 78-60

% pts won on second serve: 47-30

Winners: 37-26

Unforced errors: 30-24

The television cameras follows Serena Wiliams back into the bowels of Philippe Chatrier, capturing her reunion with coach and partner Patrick Mouratoglou.

Williams is too shattered to lift her arms to hug the Frenchman. She looks out on her feet. As she has for the whole of the match.

Mouratoglou points the way to somewhere out of shot - possibly the medicine cabinet.

Piers Newbery
BBC Sport at Roland Garros

"It was Williams who began the match close to tears, it's Bacsinszky who leaves the court in floods. She had looked on course for a first major final but Williams somehow managed to hit back from a set down for the fourth time this tournament - the first time she has done that at a Grand Slam. Coach Patrick Mouratoglou gives her a hug backstage and then guides her gingerly down the stairs away from the cameras."

Rebecca: Serena is a genius. Her antics have kept the crowd sympathetic to her. Otherwise they would have been cheering for the Swiss player.

Anuj, Harrow: All the Serena critics should show some more respect. This is the greatest female player of all time! Why would she need to fake an illness to gain an advantage?

Martin H, Coventry: Suspect that Serena will be picking up the trophy on Saturday in Paris and an Oscar in Hollywood later in the year.

Serena Williams: "I don't know how I did it. If I was going to lose, I didn't want to lose without a fight. I just tried to find some energy form somewhere. I hope I will get better before Saturday. I am ill."

Image source, Getty Images

Well, that was a hard day at the office.

One extraordinary cross-court pass, from well out wide and a split legged sliding stance, was the sort of thing that Williams would be proud of at full fitness.

She sways and staggers to her chair after getting some sincere and sporting congratulations from Timea Bacsinszky.

Bacsinszky is strugging to hold back tears. So is Williams. Not a dry eye on the court.

Image source, EPA

Timea Bacsinszky has come off the boil certainly, but Serena Williams is just slinging pure power off either wing.

She crashes away a forehand on the first of two break points at 15-40.

Off she slopes towards the changeover chair. Twenty-seven minutes on the clock for this set and a lot of that has been taken up by Williams's go-slow between points.

Image source, EPA

Heaving shoulders, hacking cough and Serena Williams is still ill.

Simon Briggs diagnoses bronchitis from the BBC Radio 5 live sports extra commentary box. But the form and prospects are looking increasing perky.

The American holds to 15 and a hotel room bed and honey and lemon drink might not be far off.

Simon Briggs
Daily Telegraph tennis correspondent on BBC Radio 5 live sports extra

"Lucie Safarova will be happy with what she's seeing at the moment. She's got a wounded animal on one side of the net and a psychologically-damaged player on the other."

Piers Newbery
BBC Sport at Roland Garros

"The momentum might have shifted dramatically on court but there's not much change off it, with Williams taking on the biggest ice towel of the day and leaning her head in her hand during the two-minute break. Bacsinszky looks unperturbed as she takes on water, perhaps resigned to the inevitable?"

Rose, Oxford: What a surprise. Back she comes. I feel sorry for who ever she plays. Not very sportsmenlike.

Curtis: Bacsinszky's forehand is pretty much non-existent, no wonder Serena is peppering it now, easy third set for Serena.

Ayo Obit: Problem is Timea is primarily a counter-puncher and Serena, even a half-fit Serena, does NOT lose to counter-punchers!

Image source, EPA

Curtains? I fear it might be.

Timea Bacsinszky skirts around a couple of break points as Serena Williams plops long on the backhand.

But she plummets a double-break behind on a third as he strays beyond the baseline.

Serena Williams hammers away a backhand punch and hollers to the skies as she backs up the break.

You could say that Timea Bacsinszky had her chances at 15-40. But are they really chances when you get two serves fizzed around your lugholes on both break points?

Williams's coach Patrick Mouratoglou is earning his corn today. He is out of his seat, clenching teeth, fist and anything else he has got in celebration. He'll give himself a hernia doing that.

Jaime, Huntingdon: Personally I suspect Serena enjoys the added attention she gets when she wins while being "unwell". All too common I'm afraid. Perhaps being so dominant makes such self-indulgence possible.

Image source, AP

That is kamikaze tennis from Timea Bacsinszky.

From 30-0 down, Serena Williams lands a whopping roundhouse inside-out forehand on return to move to 30-30.

No need for panic. Plenty of margin for error.

But Bacsinszky loses her composure quite dramatically, cracking two inviting mid-court dollies, bouncing high and gentle for her to put away, outside the lines.

Williams with a freebie of a break.

John Head, London: Serena is always most vicious when up against it. Memories of Australian Open quarter-final (2010) with Azarenka coming to the fore. She was 6-4 4-0 down in that one, I'd imagine this is not cause for concern to her.

Image source, Getty Images

Out they come for the third...

Serena Williams is still not raising her pace above octogenarian levels if there is not a live tennis ball to chase.

RieruM: If there's one thing I've learned from Roland Garros 2015, is that if Serena loses the first set it doesn't mean much!

Michael S: Serena to make a miraculous recovery and win the third set 6-0?