Victoria Azarenka won an incident-packed final against an injury-hit Li Na to successfully defend her Australian Open title and retain the world number one ranking on Saturday.

After a scrappy match marked by boos for Azarenka, a break for Australia Day fireworks and two painful falls for China's Li, the Belarusian top seed dissolved in tears when she sealed the 4-6, 6-4, 6-3 win.

Li required two medical timeouts, when she twice twisted her left ankle and also banged her head on the court, in a match also interrupted for nine minutes at a crucial stage by the fireworks.

Azarenka also overcame a pro-Li crowd that was clearly unimpressed by her controversial medical timeout in the semi-finals, which she took after blowing five match points.

Gutsy

It was a gutsy effort from the 23-year-old as she came back from a set down and sealed it on her first match point in 2hr 40min to clinch her second Grand Slam title.

"It's been a real long two weeks," Azarenka said. "I will always keep very special memories of this court. It will be in my heart forever. The last thing I want to say is, happy Australia Day everybody."

Meanwhile Li will count herself desperately unlucky after she twisted her ankle in the second set, and then went over heavily on it again after the fireworks, banging her head and appearing dazed before continuing.

"Congratulations to Victoria," said Li, who had tears in her eyes after the match. "Fantastic result here for two years, so well done."

Li, 30, first twisted her left ankle while leading 6-4, 1-3. She hobbled to her courtside chair for the ankle to be strapped.

Leading 2-1 in the third set, and playing the first point after the fireworks display, Li again tumbled over on the ankle, hitting the back of her head on the playing surface.

She required another medical timeout for possible concussion and neck problems. After the match, Li was understandably emotional, having fallen short in her bid to become the oldest female Australian Open champion.