Romania's Simona Halep celebrates as she defeats Karolina Pliskova of the Czech Republic during their semifinal match of the French Open tennis tournament at the Roland Garros stadium, Thursday, June 8, 2017 in Paris.
Not since Mima Jausovec in 1983 has an unseeded player reached the French Open final, while Ostapenko is the first Latvian grand slam finalist and the youngest at any slam since Caroline Wozniacki eight years ago.
Overwhelmed by the second seed's power in the second set, Halep regained the momentum in the decider, frustrating her opponent with her ability to soak up punishment.
After advancing to the semifinals of the French Open Grand Slam tennis tournament on Tuesday, becoming the first lady tennis player from Latvia to ever do so, Alona Ostapenko said that this achievement is something which is hard to believe, but called tomorrow's match on her birthday as "exciting".
Halep could have let watching a break point for 5-1 deteriorate into falling back on serve in the third cloud her mind, but she rebounded by immediately getting the break back and serving out the match.
Mixed in with her scintillating winners, including forehands faster than anything men's world number one Andy Murray has managed here so far, were 45 unforced errors, some of which could have been included in a video nasty.
"I was always playing aggressive and hitting the ball when I have a chance", said Ostapenko, who smacked 50 winners to Bacsinszky s 22.
And another ferocious forehand helped her break back as Bacsinszky rallied at the start of the second.
There were a couple of early double faults from Pliskova and a sprightly Halep went a break up at 2-1 when the second seed drilled a backhand into the tramlines under pressure.
Manchester United make Victor Lindelof the most expensive defender in their history
United are also expected to get a deal over the line for Real Madrid forward Alvaro Morata in the coming days. United do not only require a new centre-back.
Dabrowski, who is from Canada, and her Indian partner fended off two match points on their way to a 2-6, 6-2, 12-10 victory over Anna-Lena Groenefeld of Germany and Robert Farah of Colombia for their first Grand Slam title.
"I'm ready to face her, and I'm ready to face another final".
In the first semifinal met the birthday girl - Jelena Ostapenko match day celebrated its 20th anniversary, and Timea Bacsinszky was celebrating his 28th birthday. "I love to play here, I love you guys, you're awesome, thanks for coming to support me".
Now the opportunity to knock Germany's Angelique Kerber off top spot falls to Halep, who will become the world's highest ranked player if she beats Ostapenko in the final.
"But I can feel that I'm in the same position".
Ostapenko, whose average forehand speed of 76 miles per hour this tournament has eclipsed that of men's world No 1 Andy Murray (73), will face either 2014 Roland Garros runner-up Halep on Saturday for the title. If it's going to happen, it's going to happen, two things at the same time.
"Today I'm just gonna have fun with my family and my friends", Ostapenko said of her birthday plans.
Ostapenko will now try to win the first senior title of her career, and history might just be on her side. "Didn't have my weapons on my side and the movement was bad", Pliskova, who next faces former French Open runner-up Simona Halep, told a news conference. "She loves this tournament". After that first set we just stuck to what we do best.