Louder and louder the groans from Halep get as the rally goes on and on. The Romanian wins it. And the next one.

Stephens now looks a little stressed. She turns away and wipes her brow.

15-30.

Image source, AFP

Chanda Rubin
American former world number six on Radio 5 live

Simona Halep has got to keep the belief, stay positive and stay focused. If she can get through this match, in these conditions, wow. She would deserve it, but she's got to battle to get there.

Halep comes within an inch of a backhand winner on the first point of this game. She looks to the skies. Plenty of frustration on her face.

That's a good hold.

Halep returns to the plan of moving forward as she was earlier in this set and it does the trick to battle through from the difficult position of 30-30.

Pressure now on Sloane Stephens. She'll serve to stay in the set in a set.

Worrying times for Halep.

She's defending right up against the line judges at the back of the court as Stephens forces her further and further back.

30-30 on the Halep serve.

Chanda Rubin
American former world number six on Radio 5 live

A set and 2-0 up in the second, Sloane Stephens probably started thinking she could be a French Open champion and she tightened up. She has had to play her way through these moments.

Image source, Reuters

Back level again. It's not simple for Stephens but she gets back on terms despite the battling, scampering efforts of Halep.

4-4, now. Halep serving at a crucial time. Let's hope she's not thinking about those three previous Grand slam final defeats now...

Well, well, well.

I did not see that coming. Loose, really loose from the world number one and she gifts Sloane Stephens the break straight back.

The American's shoulders slumped at the end of the previous game but now she's bouncing around, shouting in the direction of her box again.

Who knows where this one is going.

Image source, Getty Images

Chanda Rubin
American former world number six on Radio 5 live

There are many fans who feel for Simona Halep not having won a Grand Slam. All the pressure is on her, world number one, two previous finals, so she is the player with everything on the line. You can imagine how much more relaxed Sloane Stephens was - an American in the final on red clay! I don't want to suggest Americans can't play on clay, but you were expecting Stephens to be the favourite.

Image source, Getty Images

Bolanle Adebola: Welcome back Simona!

Joel Newnham: Simona deeply sensing and playing off of Sloane's fatigue now but then it can become too easy

We could be in Bucharest rather than sunny Paris. The Romanian flags are flying once more because Simona Halep is well on her way to a remarkable turnaround in this set.

She takes the break point which gives her a fourth game in a row.

Sloane Stephens steps up to the baseline to serve with things going against for her the first time in this match.

The pair exchange points at the start of the game before Halep sends a forehand winner thudding into the backboards behind Stephens.

"Si-mo-na, Si-mo-na," chant the crowd again. Another break point for Halep.

Image source, EPA

Jonathan Jurejko
BBC Sport at Roland Garros

Is that the sound of momentum shifting? Ten points on the bounce for Halep, helped by that double fault from Stephens - the first of the match - in the fourth game.

The Halep fans might be the more vocal - as we hear another 'Simona! Simona! Simona!' right on cue - but there is plenty of support for Stephens too.

The Chatrier crowd want three sets for their money today.

Is Sloane Stephens tiring all of a sudden? Another game to love for Simona Halep. That's 11 of the last 12 points to the Romanian.

The set has turned on its head. Halep now has the momentum.

Image source, Reuters

Philip Studd
BBC tennis reporter on Radio 5 live in Paris

These players have never contested a final set. The crowd are hoping that trend is reversed today.

The slightest dip from Stephens and Halep pounces. She takes the break to love.

Don't go anywhere folks, this final is right back on.

Now then. THREE break points for Halep.

This plan is working for Halep. A smash at the net gives her the first point of Stephens' service game.

Now a double fault from Stephens, just her third of the tournament.

All of a sudden she has been forced to think by the newly aggressive Halep. 0-30.

Chanda Rubin
American former world number six on Radio 5 live

If I was Simona Halep's coach right now, I would tell her to be more aggressive. She needs to keep that up until the final point.

You can sense the crowd want something special from Halep to latch on to here.

The Romanian has decided she has to mix things up. Three times she follows a groundstroke into the net to win a point and take the game.

The crowd like what they see. A hefty roar as the players head to their chairs.