Melbourne - Victoria Azarenka won an incident-packed final against an injury-hit Li Na to successfully defend her Australian Open title and retain the world No 1 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.VIDEO: Women's Australian Open finalAzarenka 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.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.Li started nervously, a double fault to start the match in a portent of the struggles to come for both players on serve. Out of 29 games, there were 16 breaks and Li finished the match with 57 unforced errors.Li had the majority of the crowd support as spectators cheered errors and double faults from Azarenka. Azarenka won games and points to muted applause, but she held firm.Azarenka won only four points in her first three service games and when a backhand from Li kissed the line, the Chinese player led 4-2 in the first set. Her eighth winner of the match, a scorching forehand, put her ahead 5-2.Serving for the set at 5-3, four unforced errors from Li earned Azarenka a reprieve but yet another service break gave Li the 45-minute first set.Azarenka skipped to a 3-0 lead in the second set but wild forehands helped Li peg back the deficit. Li won five straight points after her first medical timeout, for treatment on her ankle, but Azarenka snuck ahead 4-2.Moving freely despite thick strapping on the ankle, Li levelled at 4-4. Azarenka was loudly booed when she angrily swatted a ball away but she ran through the next two games, holding to love for the match to be a set apiece.When they resumed the third set after the fireworks, Li again fell and required medical treatment.But she won five straight points and held a break point for 3-1 in the third set, before Azarenka peeled off groundstroke winners to hold.Azarenka broke Li for 4-2 and started producing her most dominant serving of the night. Sneaking to 5-3, the 16th break of the match ended Li's courageous performance.Azarenka became only the fourth active player to hold two or more majors, joining Serena Williams with 15, Venus Williams with seven, Maria Sharapova with four and Svetlana Kuznetsova with two.