Second seed Petra Kvitova fought back from a set down to beat fellow Czech Katerina Siniakova and reach the last 16 of the Dubai Tennis Championships.
The two-time Wimbledon champion, 28, won 6-7 (3-7) 6-4 6-4.
Russia's Viktoria Kuzmova, 20, knocked out seventh seed Kiki Bertens, 27, to go through 6-2 4-6 7-6 (8-6).
American Sofia Kenin, 20, also progressed with a 6-3 2-6 6-4 victory at the expense of Russia's 21-year-old 11th seed Daria Kasatkina.
Meanwhile, Taiwan's Hsieh Su-wei, 33, saw off Belarus' Aliaksandra Sasnovich, 24, 6-1 6-2.