Simona Halep and Angelique Kerber are set for a sequel to their pulsating Australian Open semi-final after a day of high drama at Roland Garros.
Serena Williams' bombshell withdrawal with a possible pectoral muscle tear handed arch-rival Maria Sharapova a walkover into the French Open quarter-finals before 2016 champion Garbine Muguruza was also handed a saloon passage through to the last eight.
Third-seeded Muguruza had barely broken sweat, leading 2-0, when her Ukrainian opponent Lesia Tsurenko also retired with injury.
While Sharapova and Muguruza can prepare for a heavyweight quarter-final stoush, Williams is now in a race against the clock to be fit for Wimbledon.
But the show rolls on at Roland Garros for Sharapova, Muguruza and fellow title hopefuls Halep and Kerber, who couldn't have been more impressive on Monday.
Halep underlined her credentials with a clinical dispatch of tournament dark horse Elise Mertens, the top-seeded two-time finalist sweeping past the Belgian 6-2 6-1 in 59 minutes.
Runner-up to Jelena Ostapenko last year and to Sharapova in 2014, Halep needed less than an hour to see off a rival boasting three trophies in 2018 plus a 12-win streak this season on clay.
"It was a great match, and the way I played gives me confidence that I did everything well," said the Romanian world No.1.
Kerber clubbed France's last hope, seventh seed Caroline Garcia, 6-2 6-3 to reach her first French Open quarter-final since 2012.
Halep dodged two match points to deny Kerber 6-3 4-6 9-7 in a cliffhanger at Melbourne Park in January, leaving the German eyeing revenge in Paris.
"I'm always looking for matches like this, to playing on big stage against the best players. This is always a big challenge for me," the German said.
Williams wasn't the only former world No.1 casualty on Monday, with rising Russian Daria Kasatkina sending Australian Open champion Caroline Wozniacki crashing out.
The pair had returned to resume their fourth-round match suspended by darkness on Sunday night.
But Wozniacki was quickly back in the locker room packing her bags after Kasatkina won three straight games from 3-3 in the second set to complete a watershed 7-6 (7-5) 6-3 victory.
Seeded 14th, the 21-year-old is through to her maiden grand slam quarter-final and next plays reigning US Open champion Sloane Stephens after snapping Wozniacki's 10-match winning streak at the majors.
"It means a lot, of course. It's my first quarter-finals in the grand slam," Kasatkina said after booking a last-eight on Tuesday with reigning US Open champion Sloane Stephens, the 10th seed.
"I already have to forget about it because I'm playing already tomorrow. Yeah, I'm already starting to think about next match."
Tuesday's other quarter-final will feature Stephens' fellow American Madison Keys, the 2017 Flushing Meadows finalist, against unseeded Kazakh Yulia Putintseva.
2018 WOMEN'S FRENCH OPEN QUARTER-FINAL LINE-UP (PREFIX DENOTES SEEDING):
1-Simon Halep (ROM) v 12-Angelique Kerber (GER) 3-Garbine Muguruza (ESP) v 28-Maria Sharapova (RUS) Yulina Putintseva (KAZ) v 13-Madison Keys (USA) 10-Sloane Stephens (USA) v 14-Daria Kasatkina (RUS)