Iga Swiatek's defence of the US Open title was ended by an inspired performance from the huge-hitting Jelena Ostapenko in the last 16.
Polish top seed Swiatek lost 3-6 6-3 6-1 to Latvian 20th seed Ostapenko during Sunday's night session in New York.
With her fearless and aggressive approach, Ostapenko hit 31 winners and forced Swiatek into a host of mistakes.
Ostapenko, who won her sole major at the 2017 French Open, will face American sixth seed Coco Gauff next.
Swiatek's 75-week streak as the women's world number one has been ended by the defeat, with Belarus' Aryna Sabalenka guaranteed to replace her after the US Open.