MARBELLA, Spain — Top-ranked Serena Williams has been upset by 95th-ranked Klara Zakopalova of the Czech Republic in a clay-court tournament in Spain.

Zakopalova won 6-4, 3-6, 6-1 Wednesday in the first round of the Andalucia Tennis Experience.

She converted seven break points in defeating the 2009 Australian Open champion. Williams won less than half her service points.