Australian Open: Aryna Sabalenka knocked out by Kaia Kanepi

Second seed Aryna Sabalenka suffered Grand Slam disappointment again as she lost a final-set tie-break to Kaia Kanepi to exit the Australian Open.

The Estonian world number 115 won an enthralling, topsy-turvy match 5-7 6-2 7-6 (10-7) at Melbourne Park.

Sabalenka, who served 15 double faults, had saved four match points on Kanepi's serve in the 10th game of the decider.

However, errors in the tie-break allowed 36-year-old Kanepi to reach her first Australian Open quarter-final.

She will play seventh seed Iga Swiatek in the last eight.

Sabalenka, who could have become world number one by winning the title in Melbourne, won the opening set for the first time in this tournament but then lost her opening two service games of the second set to surrender the advantage.

Kanepi, who has now reached the quarter-finals of all the major tournaments, broke first in the final set but Sabalenka, 23, hit back to level at 4-4.

In the next game, Sabalenka's service troubles surfaced again with three double faults giving Kanepi the opportunity to serve for the match.

She looked set to close it out when she moved 40-0 up but Sabalenka fought back again, with the match ultimately decided by a first-to-10 tie-break.

Kanepi started to celebrate prematurely when she moved 9-7 ahead but, after realising her mistake, secured victory on the next point.