Third seed Halep beats second seed Pliskova 6-4 3-6 6-3
Ostapenko beat Bacsinszky 7-6 (7-4) 3-6 6-3 in first semi-final
Ostapenko becomes first unseeded player to reach French Open final since 1983
Listen to online-only radio commentary of second semi-final
*Ostapenko 7-6 (7-4) 3-6 4-3 Bacsinszky
Can Timea Bacsinszky hold her serve? Don't be daft.
Jelena Ostapenko wins the 15th break point of this match as she cracks down another forehand winner.
It'll be first to hold wins at this rate...
Piers Newbery
BBC Sport at Roland Garros
The winner-or-bust nature of Ostapenko's game is clear in the tournament statistics - she leads in terms of return winners with 40, but trails well behind Bacsinszky in terms of return points and games won. It's basically all or nothing off that first strike. At the same time she is creeping up the aces charts and now stands third with 18 behind Garcia (22) and Pliskova (21), but doesn't feature among those winning most of their service games.
Ostapenko 7-6 (7-4) 3-6 3-3 Bacsinszky*
Quelle surprise.
Timea Bacsinszky is back level. The Swiss 30th seed defends her baseline with dogged determination, eventually grinding a frustrated Jelena Ostapenko down.
The Latvian can't believe these balls are coming back. She drops her racquet to the red clay, folds her arms like a petulant child and mutters to herself.
As you were...
*Ostapenko 7-6 (7-4) 3-6 3-2 Bacsinszky
I still wouldn't like to call which way this one is going to go. If you fancy a bet you might as well toss a coin.
Another game, another chance of a break...
Ostapenko cracks a forehand winner down the line for deuce, but then scrunches her face up in disappointment when she loses the next point.
A winner helps Bacsinszky cling on to her serve, and Ostapenko's face tells the story. She knows that was a chance. Especially when her serve is more fragile than a box of cheap china tea sets.
Ostapenko 7-6 (7-4) 3-6 3-1 Bacsinszky*
Finally! Our first hold of the deciding set goes the way of Jelena Ostapenko. But it took some doing.
Bacsinszky has the Latvian on the rack as they slug it out in a tough eight-minute-plus game.
There is more heaving between them than a tug o'war, Ostapenko eventually pulling the Swiss over after five deuces.
Image source, AFP*Ostapenko 7-6 (7-4) 3-6 2-1 Bacsinszky
Is anyone going to hold serve? Again?
Timea Bacsinszky fails to back up her break and, again, Jelena Ostapenko is in the box seat in this final set.
Image source, AFPOstapenko 7-6 (7-4) 3-6 1-1 Bacsinszky*
That means there have been 11 break points won in this match - only once has that break been supported by a hold.
Make that 12.
Jelana Ostapenko has only won 50% of her service points and again it is dismantled. Or, more accurately, it is dismantled by herself.
Three more unforced errors hand a break to love to the Swiss.
Image source, Getty Images*Ostapenko 7-6 (7-4) 3-6 1-0 Bacsinszky
Who's going to last the distance then? Bacsinszky has the edge in terms of history, winning 53 of her 86 three-set matches, while Ostapenko has only won 50% of her 32 matches which have gone all the way.
The Latvian isn't bothered about stats. Not when she is breaking Bacsinsky's serve in the present.
Two forehand winners seal an early advantage for the Latvian...
Image source, ReutersOstapenko 7-6 (7-4) 3-6 0-0 Bacsinszky*
Bacsinszky nips off quickly to the ladies', while Ostapenko sits in her seat and nearly gets soaked by an on-court sprinkler.
Into the decider...
Ostapenko 7-6 (7-4) 3-6 Bacsinszky
Bacsinszky doesn't need to hold another serve, instead she has gone and broken Ostapenko for the sixth time in this match.
The Swiss piles on the pressure to clock up two break points, Ostapenko saves one, but the Latvian cracks on the second.
A double fault from Ostapenko ends the set with a whimper.
Image source, EPA*Ostapenko 7-6 (7-4) 3-5 Bacsinszky
Jelena Ostapenko plays like she been on charge all night. She has some serious power.
The unseeded Latvian has Bacsinszky swinging back and forth across the baseline like a pendulum in deuce, the Swiss 30th seed's dogged defence showing that her injured knee is standing up well to everything being thrown at her.
Finally it is Ostapenko who buckles, cracking an overhead volley into the net.
A shriek from the 20-year-old, a groan from the Chatrier crowd, a straight face from Bacsinszky...
Image source, Getty ImagesPiers Newbery
BBC Sport at Roland Garros
Ostapenko might be being hailed as the bright young thing but she's positively middle-aged compared to the youngest player ever to win a match at Roland Garros - Steffi Graf, aged 13 years and 342 days, in 1983. Bacsinszky certainly has the edge in experience and that might be starting to tell. A woeful second-service points success rate of 35% needs to change for Ostapenko.
Ostapenko 7-6 (7-4) 3-4 Bacsinszky*
Bacsinszky clenches her fist, close to her face, muttering something positive to herself as Ostapenko lashes her 28th unforced error of the match.
Advantage Bacsinszky... she's got the break.
*Ostapenko 7-6 (7-4) 3-3 Bacsinszky
Now then. Could this be a match-swinging moment? Ostapenko cruises into a 40-0 lead with a ferocious forehand winner, but then lets Bacsinszky sneak in through the back door to level.
A double fault from the Latvian takes us into deuce...
Image source, AFP*Ostapenko 7-6 (7-4) 3-3 Bacsinszky
Timea Bacsinszky seems to be moving alright, by the way, after needing that medical timeout early doors.
The Swiss 30th seed's right knee is heavily strapped, but Jelena Ostapenko doesn't get her running too much in this game.
A much-needed easy hold for Bacsinszky.
Ostapenko 7-6 (7-4) 3-2 Bacsinszky*
Ostapenko holds her hand up to Bacsinszky after a walloped mis-hit confuses the Swiss, who can only bat the ball back into the tape.
She doesn't mean it. Who does? It has got to be one of the most insincere gestures in sport.
Anyway, it is another hold. On we go...
Image source, Getty Images*Ostapenko 7-6 (7-4) 2-2 Bacsinszky
Ostapenko is so much fun to watch. Wonderful winners, little consistency, emotional body language.
An unhappy shrug of shoulders greets another unforced error as Bacsinszky holds to 15.
Image source, Getty ImagesOstapenko 7-6 (7-4) 2-1 Bacsinszky*
We have a hold! And a very impressive one at that.
Three backhand winners, with an ace sandwiched in-between, sees Jelena Ostapenko consolidate her break in the previous game.
Piers Newbery
BBC Sport at Roland Garros
Bacsinszky is a popular figure around these parts as a two-time semi-finalist and with plenty of Swiss travelling support, but the locals have taken to Ostapenko in a big way. A fresh face with an attacking game, she has yet to feel any pressure it seems. Latvia's last player of note was Ernests Gulbis, a semi-finalist here and one of the most quotable men in tennis, but Ostapenko looks capable of outdoing her compatriot at just 20 years old.
Image source, Getty Images*Ostapenko 7-6 (7-4) 1-1 Bacsinszky
Fourteen games, eight service games lost. Chatrier has seen more breaks than your local A&E ward.
Ostapenko's game is perfectly illustrated by the unforced errors/winners stat. While she has cracked 24 winners so far, she has also made 19 errors.
Another backhand winner from the Latvian forces deuce, and then Bacsinszky's serve disintegrates at the worst possible time.
A double fault hands over a break point, which Ostapenko takes with, ye, you've guessed it, a backhand winner.
Image source, Getty Images