Serena Williams stunned by Makarova
Serena Williams' Australian Open campaign is over after she was sent spinning out of the opening grand slam of the year by Russia's Ekaterina Makarova.
The five-time winner was unable to find her rhythm during the match, hitting 36 unforced errors in a 6-2 6-3 defeat.
It is the first time Makarova has reached the final eight of a grand slam, and she had a solid service game to thank for her milestone win. Makarova will now face either Maria Sharapova or Sabine Lisicki.
Petra Kvitova booked her place in the Australian Open quarter-finals with a 6-2 7-6(2) victory over Ana Ivanovic.
The reigning Wimbledon champion survived a surprising slump toward the end of the second set, allowing Ivanovic to rattle off three straight games to push the world No. 2 into a tiebreaker.
However, a nervy double-fault early in the deciding tiebreaker handed the momentum back to Kvitova, who duly went on with the job.
Kvitova's win sets up a quarter-final with Sara Errani, who easily accounted for Jie Zheng. The 47th-ranked Errani remained composued in her firs fourth-round slam appearance, while it was a match to forget for Zheng as she hit 47 unforced errors.