Aryna Sabalenka falls to Kaia Kanepi in three sets in Australian Open upset
World number two Aryna Sabalenka has bowed out in the biggest upset of the Australian Open so far, falling to Estonian veteran Kaia Kanepi under a shower of double faults.
A semifinalist at both Wimbledon and the US Open last year, Sabalenka was heavily favoured to advance to the quarterfinals.
But her serve let her down again, as it had done throughout her latest campaign at Melbourne Park.
It played a role in allowing Kanepi to fight back from a set down to secure the shock 5-7, 6-2, 7-6 (10-7) victory.
At 36, the world number 115 is the oldest player in the women's draw.
Sabalenka twice recovered from a break down during the third set and survived four match points before the rivals went to a dramatic tiebreak, which Kanepi thought was over early when she went ahead 9-7.
One point later, the boilover was complete.
Sabalenka committed 15 double faults for a tournament total of 56 in four matches.
The Belarusian's tally is more than double that of the next worst offenders, with Paula Badosa (24) and Danielle Collins (20) well behind.
Kanepi has now taken down two seeds on her way to the quarterfinals, having ousted 2016 champion Angelique Kerber in the first round.
It is Kanepi's deepest run at the Australian Open, matching her pair of quarterfinal finishes at each of the other majors.
She will meet seventh seed Iga Świątek in the last eight.
Świątek came from a set down to edge Romania's Sorana Cirstea 5-7, 6-3, 6-3 in a baseline-dominated affair earlier on Monday night.
AAP