MADRID, April 8 (Xinhua) -- World number one Serena Williams was upset by Klara Zakopalova of the Czech Republic 6-4, 3-6, 6-1 in the first round of the Andalucia Tennis Championships on Wednesday.

    The American top seed dropped serve seven times confronting her rival who is ranked 95th in the world.

    An injury-hit Williams also suffered a heavy blow by the 19-year-old Belarussian Victoria Azarenka in the final of the Sony Ericsson Open on Saturday.