Defending champion Kristyna Pliskova was among five seeds to suffer a second-round exit in the Tashkent Open on Wednesday.
Pliskova claimed her solitary WTA singles title on the hard courts in Uzbekistan last year, but there will be no repeat after Kurumi Nara beat the top seed 7-6 (7-5) 6-1.
Czech Pliskova's hopes of becoming the first player to win the Tashkent Open twice were ended by a player ranked 68 players below her.
Pliskova struggled on serve and the world number 109 from Japan made her pay, claiming the ninth mini-break of a tie-break to win the first set.
Both players were broken twice in a first set which swung one way and the other, but it was a different story in the second, Nara racing into a 4-0 lead before serving out the match to love.
Third seed Tatjana Maria also missed out on a place in the quarter-finals, losing 6-3 7-5 to Aryna Sabalenka.
Marketa Vondrousova, Ekaterina Alexandrova and Nao Hibino were the other seeds to bow out with defeats to Stefanie Voegele, Kateryna Kozlova and Kateryna Bondarenko respectively.
Second seed Timea Babos beat Denisa Allertova 6-3 6-3, while Aleksandra Krunic and Vera Zvonareva were also second-round winners.