Russell Fuller
BBC tennis correspondent on Radio 5 live sports extra

"Sheer bloody-mindedness, sheer brilliance, from Serena Williams when she is clearly not 100%. We are going the distance."

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Serena Williams racks up two set points at 40-15.

Timea Bacsinszky shoots them down.

But Williams rolls out the heavy artillery, booming down a bazooka ace to set up a third that proves the charm. Into a decider.

Serena with the momentum or Timea without the illness? Let's find out.

Coach Patrick Mouratoglou leads the cheer squad as Serena Williams sniffs blood, advances and slaps away the forehand drive volley at break point and 30-40.

Timea Bacsinszky is being pulled out of shape by the top seed's power when the rallies are allowed to develop.

She doesn't seem able to destabilise Williams, or force her into lateral movement, as she did in the first set.

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David Jack: People making ludicrous claims that Williams is faking her illness. Yeah, cos that's a brilliant tactic isn't it.

PS: Sick of Williams' antics which have been fairly consistent last few years.

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

"Tactically it is quite a dilemma for Bacsinszky. It is always an awkward scenario when your opponent is struggling. The dilemma is that you try to work them around the court, get them running and losing more energy, but then you can lose your own game."

Serena Williams may only be operating in second gear, but she is red-lining it all the way in the shots that he does hit.

Successive crackerjack aces down the middle seal the game and save the American from having to expend any more energy then she has to.

She is ahead on the scoreboard again. A crucial time in the match now. The last thing that Bacsinszky should do is give her opponent the tonic of a break.

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Nick Powell: Can't tell if Serena is faking or not, I suspect not, but how many times have we seen her in this state before dominating.

Deary me.

Timea Bacsinszky has been all-out attack so far in the match and it has served her well.

But the purple patch fades slightly as the Swiss boshes down the line and out to allow Serena Williams to 15-40 and two break points.

She converts the first as Bacsinszky fails to crowbar a backhand off the dust.

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Piers Newbery
BBC Sport at Roland Garros

"While Bacsinszky holds up a deflated ball to the umpire at the changeover, her opponent is looking similarly beaten on the opposite chair. Williams cannot sit up straight and is coughing and spluttering, looking tearful once again."

Just in reply to Philip in the tweet below, I don't think that anyone thinks that Serena Williams is faking an illness.

It is just the way she seems to be coping with it is to act out every cough, splutter and ache in triplicate.

There is more swooning and swaying at the changeover.

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Russell Fuller
BBC tennis correspondent on Radio 5 live sports extra

"I still think there's plenty of mileage left in this match - but it is getting very, very tight for Williams."

Timea Bacsinszky is all over the Serena Williams serve like a an angry rash.

Two break points have already disappeared down the swanny, when the Swiss breaks out a drop-shot return winner to Serena Williams' rocket. Extraordinary.

Williams sees off another two break points but finally at the sixth time of asking, Bacsinszky has the break as Williams cuffs a backhand wide.

Philip Farrell: Come on guys, two text messages implying Serena is faking it seems a bit harsh. She doesn't look well.

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One forehand error and three off the backhand seal Serena Williams's demise to love.

Plenty of pop in Timea Bacsinszky's groundstrokes to force those mistakes, but it looks like Williams has suffered a set-back.

There has been more twists and turns in her performance - and dare I say it hammy acting - than a Brazilian telenovela.

Maybe there was a swig of WD40 amid all the isotonic.

Serena Williams looks like she is moving a little more freely suddenly, Her foot movement is busier, her forehand arm is swinging easier and she holds her serve with relative ease.

Have we started the upturn of the Williams U-turn in this match?

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Chris, London: Amazing how Serena can look like she will collapse in between points and yet still the ball as hard as always during the point.

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

"Serena is making a lot of hand gestures - 'all is against me,' she says. 'Even the gods are smiling on my opponent.' It would be an amazing comeback from Serena considering all the spluttering and almost fainting she is doing. Assuming she is not exaggerating her illness, it would be remarkable to get out of this position."

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Serena Williams looks exasperated as a Timea Bacsinszky forehand snags the wire looping up, over her shoulder and in to seal the game for the Swiss.

I think that Williams is playing this match to an internal soundtrack of sobbing violins. Everything is against her.

If and when she stops feeling sorry for herself and starts to fight back against whatever is afflicting her, she has a chance.

John, London: Granted, Serena Williams doesn't look well - but seems like she's employing the old tactic of 'Laying it on thick' - cue miraculous recovery.

Mark Johncock: I may be cynical but what are the odds of Serena suddenly feeling better if she manages to get ahead in second set?