REIGNING champion Kim Clijsters admits her title defence hangs in the balance after aggravating an ankle injury in a gutsy three-set defeat of fifth seed Li Na.
Clijsters (inset), seeded 11th, fought back from a set down to defeat the Chinese French Open winner 4-6, 7-6 (8-6), 6-4 and reach the Australian Open quarter-finals.
But the Belgian, who meets top seed Carline Wozniacki next, needed an ice bath and heavy strapping immediately afterwards and addressed media with her foot elevated to relieve swelling.
Clijsters said: “I have the best people around me to take care of me and to make sure that this is hopefully not going to get any worse.”
Wozniacki smothered a late comeback from 13th seed Jelena Jankovic. Meanwhile, Victoria Azarenka will face Agnieszka Radwanska.