Caroline Wozniacki had no answer to the brilliance of the unseeded Camila Giorgi in Toyko, ending her dreams of a third successive title.
Caroline Wozniacki was well below her best as the Australian Open champion suffered a straight-sets defeat to Lesia Tsurenko on Thursday.
Caroline Wozniacki and Jelena Ostapenko headed into the final major of the year on losing streaks, but made it into round two.
Simona Halep was leading 4-3 and 30-15 in the final set against Alja Tomljanovic when rain washed out play on Wednesday.
Rising Belarusian Aryna Sabalenka knocked out world number two Caroline Wozniacki in three sets in Montreal on Thursday.
Caroline Wozniacki's first match since Wimbledon ended in a three-set defeat to Aryna Sabalenka in Montreal.
Sloane Stephens advanced, but defending champion Ekatarina Makarova was sent packing on a mixed day for seeded players in Washington.
Australian Open champion Caroline Wozniacki will not start her hard-court season in Washington due to a leg injury.
Pam Shriver berpendapat bahawa dua bintang tenis wanita, Caroline Wozniacki dan Simona Halep, boleh mengubati kekecewaan sebelum ini dengan memenangi gelaran Grand Slam pertama dalam kejohanan Terbuka Australia.
Pemain tenis Denmark, Caroline Wozniacki, terlepas peluang meraih kejuaraan apabila tewas dalam aksi final Terbuka Sweden di tangan pemain ke-56 dunia, Katerina Siniakova, di Bastad.