When World No.31 Timea Bacsinszky takes on World No.47 Jelena Ostapenko in today's first match, it will be the first Slam semifinal between players yet to reach a final since Simona Halep beat Andrea Petkovic at Roland Garros in 2014.
The No.1 ranking is on the line in today's second match: No.2 seed Karolina Pliskova will take it if she wins. No.3 seed Simona Halep needs a title to rise to the summit. If Halep beats Pliskova but loses the final, Angelique Kerber will retain the top spot.
The winner of the match between Timea Bacsinszky and Jelena Ostapenko will be ranked in the Top 20 after Roland Garros - which would be a re-entry for the Swiss player, who peaked at No.9 in 2016 but fell out of the Top 20 this April. Ostapenko, meanwhile, is guaranteed to set a new career high - currently it's No.33, set in January.
Today's match marks the first time in 2017 that Simona Halep has played a Top 5 opponent.
Jelena Ostapenko, the first Latvian woman to ever reach a Slam semifinal, is bidding to become the first unseeded player to reach the Roland Garros final since Mima Jausovec, runner-up to Chris Evert in 1983, and the youngest player in a Slam final since Caroline Wozniacki at the 2009 US Open.
Timea Bacsinszky had not made a quarterfinal of any kind in 2017 prior to the French Open - indeed, not since her semifinal run in Gstaad last July.
Simona Halep has spent the least amount of time on court of the four semifinalists, at six hours and 53 minutes with just one set lost. Jelena Ostapenko has racked up the most court time with seven hours and 58 minutes, having lost three sets en route - to Louisa Chirico in the first round, Samantha Stosur in the fourth round and Caroline Wozniacki in the quarterfinal.
Jelena Ostapenko's presence in the last four marks the 16th straight Slam featuring a debut semifinalist. The streak stretches back to Wimbledon 2013, when Kirsten Flipkens made the semifinals before losing to Marion Bartoli.
Since the introduction of 32 seeds at Slams (at Wimbledon 2001), there have been 23 unseeded semifinalists. Ostapenko is just the fourth of those at Roland Garros following Clarisa Fernández in 2002, Nadia Petrova in 2003 and Kiki Bertens in 2016.
Jelena Ostapenko has made three WTA Tour finals (Québec City 2015, Doha 2016 and Charleston 2017), but is yet to win a title. The last player to win their debut title at Roland Garros was Gustavo Kuerten on June 8, 1997 - the day Ostapenko was born.
Gabriela Dabrowski, the doubles World No.20, will play her first Slam final alongside Rohan Bopanna in the mixed doubles championship match today. Prior to Roland Garros, her best Slam showings had been two mixed doubles quarterfinals and two women's doubles third rounds - she equalled the latter here as well, partnering Xu Yifan. Dabrowski owns four WTA Tour doubles titles, the biggest of which also came with Xu this year in Miami.
By contrast, her opponent, Anna-Lena Groenefeld will be appearing in her fourth mixed doubles Slam final and second with partner Robert Farah, with whom she was also runner-up at Wimbledon last year. Groenefeld was the champion at Wimbledon in 2009 (alongside Mark Knowles) and Roland Garros in 2014 (alongside Jean-Julien Rojer).
The WTA Insider team has broken down the match-ups and potential deciding factors for both semifinals in our Insider Analysis. Here's what the stats say according to the New York Times, and here's how RolandGarros.com sees the Halep vs Pliskova match.
Jelena Ostapenko's coaching relationship with former Top 20 player Anabel Medina Garrigues has piqued the interest of many fans - particularly given that their playing styles are so contrasting. Find out more about how clay expert Medina Garrigues has helped the explosive Ostapenko.
It's not all about Roland Garros in the tennis world this week - find out how Sara Errani and Johanna Larsson are getting on in the WTA 125K Series event in Bol.
Relive how Jelena Ostapenko and Timea Bacsinszky reached today's first semifinal.