SEOUL, South Korea (AP) - Maria Kirilenko of Russia withdrew from a second-round match at the Korea Open on Wednesday because of a back injury.

Organizers said Kirilenko complained of back pain during a match with South Korean player Lee So-ra.

Nadia Petrova of Russia defeated Lourdes Dominguez Lino of Spain 6-2, 6-4 in her opener, while Kaia Kanepi of Estonia beat Galina Voskoboeva of Kazakhstan 6-2, 6-2, to reach the quarterfinals.