BRISBANE: Kei Nishikori is putting his preparation for the Australian Open above everything else at the start of the season, including his birthday celebrations.

Despite spending his 27th birthday on December 29 in transit in order to get in good preparation for the Brisbane International, Nishikori was still a little rusty in his season-opening match against Jared Donaldson before holding off the American qualifier 4-6, 6-4 6-3 on Wednesday to reach the quarterfinals.

The third-seeded Nishikori, a three-time semifinalist in Brisbane, had a first-round bye and started the second round confidently by racing to a 4-0 lead. But Donaldson responded and won the next six games to take the opening set in less than an hour, breaking Nishikori three times.

After jumping to a 3-0 lead in the second, Nishikori dropped another service game but this time was able to limit the damge and used his experience in pressure situations to calmly hold on and win the second and third sets. He will next play either eighth-seeded David Ferrer or Jordan Thompson.

Nishikori went almost immediately back out to join Dominic Thiem in a doubles quarterfinal match against Gilles Muller and Sam Querrey.

Sixth-seeded Lucas Pouille was trailing Kyle Edmund 6-3, 3-1 when he retired from their second-round match. Pouille had treatment for blisters on his feet after winning the first game of the second set, then lost three games before signaling to the umpire that he could not go on.

A day after becoming the first player born in the 2000s to win a main draw match at an elite WTA event, Destanee Aiava lost to two-time Grand Slam winner Svetlana Kuznetsova in the women's second round.

Fifth-seeded Kuznetsova beat the 16-year-old Australian high school student 6-4, 6-3, starting with a service break in the opening game.

Aiava will return to her hometown Melbourne, where she will play an exhibition tournament next week to continue preparations for her first Grand Slam event. She has a wild-card entry for the Australian Open, where she is set to be the first player born this millennium to play a Grand Slam main draw match.

Aiava said it was a little daunting taking on a two-time major winner.

"It's pretty scary," she said. "I learned a lot out of that match."

Aiava advanced through qualifying, and then beat 31-year-old Bethanie Mattek-Sands in three sets in a first-round match that spanned two rain-interrupted days to set her WTA milestone. The experience has been valuable, she said, giving her "Some confidence, maybe, in my game and myself, knowing that I do belong here."

Kuznetsova will play French Open champion and fourth-seeded Garbine Muguruza in the quarterfinals.

Second-seeded Dominika Cibulkova came from a set and a break down to beat Zhang Shuai 2-6, 6-4, 6-4 in her first competitive match since beating No. 1 Angelique Kerber to clinch the season-ending WTA Finals title. No. 8-seeded Roberta Vinci beat Misaki Doi 6-4, 6-2 in another second-round match.

Kerber will open her 2017 later Wednesday against Australian wild-card entry Ash Barty in a night match.