Former Australian Open champion Caroline Wozniacki lost in the French Open first round to Russian world number 68 Veronika Kudermetova.
The Danish 13th seed lost 0-6 6-3 6-3 on Philippe Chatrier despite winning the opening seven games in a row.
Wozniacki won 62% of the total points in the opening set but crumbled in the second and was broken three times.
She fell 3-0 down in the decider as she lost a first-round match in Paris for only the third time since 2007.
The Dane, a two-time quarter-finalist at Roland Garros, withdrew from her first-round match against American Danielle Collins at the Italian Open earlier this month because of a leg injury.
It was the second successive tournament Wozniacki retired early from after she pulled out of her opening match at the Madrid Open with a back injury.
She had won just four matches on clay before her meeting in Paris with Kudermetova, who was playing in only her second Grand Slam main draw.
Wozniacki’s exit comes after Czech sixth seed and Australian Open finalist Petra Kvitova withdrew on Monday with an arm injury, while Wimbledon champion Angelique Kerber suffered a shock 6-4 6-2 defeat to world number 81 Anastasia Potapova on Sunday.
Kudermetova will now face Kazakh world number 99 Zarina Diyas or France’s Audrey Albie, ranked 289th, in the second round.
Elsewhere, Dutch fourth seed Kiki Bertens comfortably defeated French world number 66 Pauline Parmentier 6-3 6-4 on Suzanne-Lenglen.
And Australian Open quarter-finalist Ashleigh Barty, seeded eighth, beat American world number 72 Jessica Pegula 6-3 6-3.