MELBOURNE - Kim Clijsters was courage personified as the defending champion shook off a painful ankle injury and saved four match points to overhaul China's Li Na 4-6 7-6 6-4 and reach the quarter-finals of the Australian Open on Sunday.

Kim Clijsters of Belgium htis a return to Li Na of China during their women's singles match at the Australian Open tennis tournament in Melbourne January 22, 2012. [Photo/Agencies]

The big-hearted Belgian rolled her left ankle at 3-3 in the first set on a scorching day at Rod Laver Arena but rejoined the battle after a lengthy medical time-out with her foot thickly taped.

In a re-match of last year's finalists, champion Clijsters stared at the abyss when 6-2 down in the second set tiebreak but reeled off six points in a row to take the set and spark a rapturous ovation from the stands.

The hard-hitting Li slumped to 4-0 down in the decider then recovered gallantly to trail 5-4 but Clijsters held to close out the match and keep her hopes alive of a fifth grand slam title in her farewell year on tour.

Clijsters next plays the winner of top seed Caroline Wozniacki and former world number one Jelena Jankovic.