Top seed and defending champion Naomi Osaka is out of the US Open after a straight-sets defeat to Belinda Bencic in the last 16 in New York.
Osaka has been carrying a knee injury and called the trainer on midway through the second set, although she was able to carry on without receiving any treatment.
However, the 21-year-old from Japan was beaten 7-5 6-4 in the round of 16 by the Swiss 13th seed.
The loss comes just two days after her victory over Coco Gauff, 15, where she showed tremendous compassion and kindness to the teenager after the match.
Bencic reaches her first quarter-final in New York since 2014, with the 22-year-old one of Martina Hingis' proteges.
Next up for Bencic is No 23 Donna Vekic, who defeated Julia Görges, 6-7 (5), 7-5, 6-3.
Vekic has never reached the quarter-final of a Grand Slam before and survived after Gorges served for the match and also squandered match points in the second set.
The loss now means both the women's and men's defending champions are out, after Novak Djokovic's exit less than 24 hours earlier.
The Serbian retired vs Stan Wawrinka through injury.
