WARSAW, Poland, May 3 (UPI) -- Defending champion Kim Clijsters Thursday lost in straight sets to Julia Vakulenko in the second round of the J&S Cup Tennis Tournament at Warsaw, Poland.
The 61st-ranked Vakulenko, from Ukraine, won by scores of 7-6 (7-3), 6-3.
Clijsters, a former world No. 1 from Belgium who is retiring at season's end, beat Russian Svetlana Kuznetsova in last year's final.
Fellow Belgian Justine Henin, the current top-ranked player in women's tennis, was a 6-1, 6-2, winner over Anna-Lena Groenefeld of Germany.
Another former world No. 1, Venus Williams of the United States, topped seventh-seeded Russian Elena Dementieva, 6-1, 7-6 (7-4); and fourth-seeded Jelena Jankovic of Serbia beat Russia's Elena Vesnina, 6-2, 7-5.
Henin plays Italy's Mara Santangelo Friday. Williams plays No. 3 seed Svetlana Kuznetsova, Jankovic faces No. 6 seed Anna Chakvetadze of Russia, and Vakulenko plays fellow Ukrainian Alona Bondarenko.
