Serena Williams crashed out of the Andalucia Tennis Experience with a shock first-round defeat to Klara Zakopalova.

The unfancied Czech broke the top-seeded American seven times on the way to a 6-4 3-6 6-1 victory in one hour 29 minutes.

Today's game marked a second loss in five days for Williams, who went down in straight sets to Victoria Azarenka in the final of the Sony Ericsson Open on Saturday.

Williams was hampered by injury in that game and looked far from her best again today, winning just 49% of points on her first serve.

Other second-round winners today were Roberta Vinci, Anabel Medina Garrigues and seventh seed Sorana Cirstea.

Italian Vinci beat Nicole Vaidisova 6-3 6-3, Medina Garrigues defeated fellow Spaniard Virginia Ruano Pascual 6-2 6-3 and Cirstea dominated the final two sets to see off Andreja Klepac 4-6 6-1 6-1.

Estonia's Kaia Kanepi won her first-round match against Silvia Soler Espinosa 6-4 6-2.