Piers Newbery
BBC Sport at Roland Garros

This match has gripped the Chatrier crowd just as Wawrinka v Murray did 24 hours ago, pitting a brilliant shot-maker up against a great defender.

Ostapenko is desperate to move forward at every opportunity, while Halep is just about managing to keep a lid on her with only one winner and two unforced errors to her name. The noise from the upper reaches of Halep's player box when she wins a game is deafening - I can't see Ivan Lendl ever taking the job.

Halep has broken the Ostapenko serve twice already. A third now will do rather nicely for the Romanian...

Image source, Reuters

Sat in the Paris sun watching the tennis at Roland Garros. Life doesn't get much better for those ticket holders on Chatrier, does it.

Especially when they are being treated to a dazzler of an opening set.

Halep's serve gets another thorough examination from Doctor Ostapenko, with the Romanian only winning a quarter of the points on her second serve.

Two forehand winners put Ostapenko 30-0 ahead, but Halep roars back with a plucky hold when the Latvian can't get a backhand from the baseline back.

Image source, EPA

Jelena Ostapenko has made 17 unforced errors so far. Simona Halep has just made one...

The world number 47 adding to that allows Halep to battle back from 40-15 to deuce, the pair becoming embroiled in a monster of a baseline rally which has Chatrier oohing and aahing like a Bonfire Night crowd.

Ostapenko wins the point to clinch the hold, bending her knees and clenching both fists as she celebrates wildly in the direction of her box.

A double fist-clench? In the eighth game? Gone big.

David Rowberry‏: Surely one of them would've asked their clothing sponsor to provide a different colour oufit.

Image source, AFP

The problem with playing Ostapenko is that she doesn't let you get into any rhythm. Halep is finding that out now. This is their first meeting remember.

The Latvian wallops another backhand winner down the line for 30-40, forcing deuce in the next point. And another brilliant backhand brings up a third break point of the match for the Latvian.

Halep digs deep, bats it off and pulls out a gutsy hold. Ostapenko threatens to demolish her racquet, then thinks again.

Image source, Getty Images

Piers Newbery
BBC Sport at Roland Garros

Confirmation, if it was required, that Romanian fans have travelled in numbers for this one as they launch into a loud burst of "Si-mo-na! Si-mo-na!" at the changeover, with flags emerging from all corners of Chatrier. It seems that the locals are siding with outsider Ostapenko, however, so she is not lacking support.

We have got more breaks here than at your local A&E ward.

Ostapenko again buckles in the game after nicking Halep's serve, a double fault putting the Romanian 40-0 ahead and then slapping a forehand into the net from the baseline.

Image source, Reuters

Camille Pin
Former tour player on BBC Radio 5 live

Ostapenko definitely has a temper. She almost behaves like she doesn't have a lot of friends. But she doesn't care, she just concentrates on her tennis.

Halep is being blown off the court at the moment. Ostapenko spanks two brutal backhands past Halep's despairing lunge, following it up with a forehand winner that takes a huge chunk of the net cord before bouncing to safety.

Two more break points for Ostapenko... Again she needs just one. Halep misses the target with a backhand and the 20-year-old world number 47 nudges ahead again...

Image source, Getty Images

A great stat was doing the rounds the other day: Jelena Ostapenko's forehand winners inher quarter-final win had more pace than Andy Murray's.

Here's another example. She blasts a forehand winner down the line so hard I half expect to see smoke on her racquet. 88mph!

That's 30-15, another rapid winner soon following for 40-15. Job done.

Camille Pin
Former tour player on BBC Radio 5 live

Halep's legs are moving well even though she's been under a bit of pressure.

It's nice for her to have people here from all over the world. She deserves it. She's a great professional.

With the crowd like this, it must be a great feeling for her.

Phew. A hold. And a very comfortable one as well.

Simona Halep finds her first serve to hold to love, a couple more backhand errors from Ostapenko helping her over the line.

"Si-mo-na, Si-mo-NA!" the Chatrier crowd appears to have more Romanians in it than Latvians...

Image source, Reuters

This is the first meeting between the two players.

Jelena Ostapenko is competing in her first French Open, while Simona Halep made her debut in Paris in 2010.

Image source, .

Reality check. Simona Halep doesn't take too kindly to being made a mug of in that opening game.

The Romanian third seed belts a forehand winner down the line for 15-0, two errors from Ostapenko teeing up three break back points.

The unseeded Latvian gamely battles back to 30-40, but then lamps a forehand wide into the tramlines.

Two games, two breaks. Back on serve...

Camille Pin
Former tour player on BBC Radio 5 live

How powerful is this girl? She's only 20 years old, has never played a Grand Slam final before and yet she's playing like Serena Williams.

The way she is dealing with his moment is unreal.

Image source, Reuters

Nerves? What nerves?

A sen-sa-tion-al start from the 20-year-old Latvian. Ostapenko is straight on the front foot, racking up three break points.

And she needs just one! Another crackerjack of a backhand down the line nicks a break in the opening game. Wow...

James Stevenson: Definitely going three sets this final today. Hopefully it's close. Heart says Ostapenko. Head says Halep.

Image source, EPA

If you're not familiar with Jelena Ostapenko's work then this stat tells you pretty much everything you need to know.

The 20-year-old Latvian has cracked 245 winners - more than any other player, man or woman, in the tournament.

However, that comes at a price... she has made a whopping 217 unforced errors. Risk and reward.

And Ostapenko cracks an early backhand winner down the line for 30-0. Early pressure on the Halep serve...

Right then. Ready? Play.

Ostapenko starts with the mind games early doors, making Halep wait on the baseline as she sits on her seat taking a last gulp of water.

The Romanian to kick us off...