Italy's Karin Knapp took down top- seeded Monica Niculescu in Tuesday's first-round action at the Tashkent Open.

Knapp beat the Romanian Niculescu by a 2-6, 6-3, 7-5 margin in a match that lasted over 2 1/2 hours.

In another upset, qualifier Donna Vekic of Croatia defeated fourth-seeded Slovak Magdalena Rybarikova 7-6 (7-3), 6-3 on the hardcourts at Olympic Tennis School.

A trio of seeded players managed to avoid the upset bug. Romanian Alexandra Cadantu, the No. 5 seed, outlasted Russian qualifier Ekaterina Bychkova 3-6, 6-4, 7-5, No. 6 seed Bojana Jovanovski of Serbia got past German Dinah Pfizenmaier 6-2, 2-6, 6-4, and eighth-seeded Galina Voskoboeva of Kazakhstan beat Serbian qualifier Vesna Dolonc 3-6, 6-1, 6-0.

Other first-round winners Tuesday were Russians Anna Chakvetadze and Vitalia Diatchenko, Romanian Irina-Camelia Begu, Japan's Misaki Doi, Greek Eleni Daniilidou and Czech Eva Birnerova, who was last year's Tashkent runner-up to Russian Ksenia Pervak. The former top-10 star Chakvetadze topped Ukrainian fellow qualifier Lesia Tsurenko 6-4, 6-3, while Begu beat two-time Tashkent runner-up Akgul Amanmuradova of Uzbekistan 6-4, 6-3 on Day 2.