Back injury knocks Kirilenko out of Korea Open

Maria Kirilenko was forced to retire from her first-round match at the Korea Open on Wednesday because of a back problem.

The second-seeded Russian had split the first two games against Korean wild card Lee So-Ra before calling it quits.

Lee advanced to a second-round match with Tamira Paszek after the Austrian posted a 7-6 (10-8), 6-3 win over Spain's Carla Suarez Navarro.

Fourth-seeded Nadia Petrova earned a 6-2, 6-4 victory over Spain's Lourdes Dominguez Lino and will face another Spaniard in the second round after Maria Jose Martinez Sanchez thumped Greek qualifier Eleni Daniilidou, 6-2, 6-3.

Second-round action also started Wednesday with a pair of matches.

Third-seeded Kaia Kanepi of Estonia cruised into the quarterfinals with a 6-2, 6-2 rout of Kazakhstan's Galina Voskoboeva. She'll next face Kiki Bertens of the Netherlands. Bertens rallied for a 1-6, 7-6 (7-3), 6-2 triumph over Spain's Silvia Soler-Espinosa.

Top-seeded Caroline Wozniacki will play her second-round match Thursday against France's Caroline Garcia.