China's Li Na advanced to the quarterfinals of the Australian Open, beating eighth-seeded Victoria Azarenka of Belarus 6-3, 6-3 on Sunday at Rod Laver Arena.
Azarenka set up match point with her fourth double-fault, then hit a backhand into the net on the next point to give Li the match.
The ninth-seeded Li was a semifinalist at Melbourne Park last year, losing to eventual champion Serena Williams in two tiebreak sets. That was Li's best performance in 21 Grand Slam events. This year, Li will face either Andrea Petkovic of Germany or 2008 champion Maria Sharapova in the quarterfinals.
Petkovic, who advanced when Venus Williams retired with a thigh injury, and Sharapova were playing their fourth-round match later on Sunday.