The top two seeds at the Japan Women's Open, Misaki Doi and Yanina Wickmayer, each suffered first-round exits in Tokyo on Tuesday.
World number 35 Doi went down 7-5 6-3 in her home city to Aliaksandra Sasnovich, a player 75 places below her in the WTA rankings. Sasnovich will now face Alison Riske.
Defending champion Wickmayer also slumped to a straight-sets defeat in the hard-court event, losing 6-1 7-6 (9-7) to Viktorija Golubic - the champion on clay in Gstaad earlier this year.
Fourth seed Johanna Larsson was able to book her place in round two, where Varvara Lepchenko awaits the Swede, courtesy of a 6-3 6-2 triumph over Sabine Lisicki.
Katerina Siniakova was a 6-1 6-4 victor over Antonia Lottner, while the day's action concluded with a hard-fought victory for qualifier Jang Su-jeong over Zheng Saisai.