BRISBANE: In the 12 months since her previous trip to the Brisbane International, Angelique Kerber won her first two Grand Slam titles and supplanted Serena Williams as No. 1 in women's tennis.

For two sets on Wednesday night, Kerber dominated as the top-seeded player should. Between those sets, she struggled with her serve against the gritty determination of local wild-card entry Ash Barty, the 2011 Wimbledon junior champion who spent nearly two years out of tennis pursuing a career in cricket following her previous appearance at the Brisbane International in 2014.

Kerber closed out a 6-3, 2-6, 6-3 win with an ace, her fifth of the match, to progress to a quarterfinal match against sixth-seeded Elina Svitolina — the only player who beat both the No. 1-ranked women (Kerber and Williams) in 2016.

"I'm so, so happy to be back in Australia — that was my breakthrough last year," Kerber said. "I'm feeling good. I mean, I have great memories from last year. Of course it was a completely different situation like 12 months ago, but to being here, starting here, that's a good thing, I think.

"It will be a different year than in 2016, but I think that I'm ready for that."

It wasn't entirely smooth for Kerber, who launched her breakout season with a run to the Brisbane final last year and went on to win the Australian Open, the U.S. Open and reach the finals at Wimbledon and the Olympics.

She fended off three break points in the first set but, with five double-faults in the second, was broken twice and allowed Barty to even the match.

Kerber regained her rhythm in the third and cut down her errors, and Barty's challenge ran out of steam.

On the men's side, second-seeded Stan Wawrinka and No. 3 Kei Nishikori advanced.

Wawrinka, the U.S. Open champion, beat Viktor Troicki 7-6 (5), 6-4 in his debut match at the tournament to move into the quarterfinals against Kyle Edmund.

From 2014-16, Wawrinka won the Chennai tournament in India without dropping a set.

"For sure it's a bit different conditions, but I don't think it will change much for the preparation for Australia," said Wawrinka, who won his first major title at Melbourne Park in 2014. "When you've been on the tour for so long, to play some new tournaments, it makes you a little bit fresher mentally."

He extended his record to 7-0 against Troicki, recovering an early break to dominate the match.

Nishikori was rusty against Jared Donaldson but found enough to hold off the American qualifier 4-6, 6-4, 6-3.

Eighth-seeded David Ferrer didn't make it that far, saving four match points on serve late in the third set before losing to Australian wild-card entry Jordan Thompson 4-6, 7-5, 7-5.

In his first ATP quarterfinal match, Thompson will play Nishikori, a former U.S. Open finalist and a three-time semifinalist in Brisbane.

Sixth-seeded Lucas Pouille was trailing Edmund 6-3, 3-1 when he retired from their second-round match because of blisters.

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 champion Svetlana Kuznetsova 6-4, 6-3 in the women's second round.

"It's pretty scary (but) I learned a lot out of that match," said the 16-year-old Aiava, adding that she had gained "confidence, maybe, in my game and myself, knowing that I do belong here."

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.

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

Second-seeded Dominika Cibulkova rallied from a set and a break down to beat Zhang Shuai 2-6, 6-4, 6-4 in her first competitive match since winning the season-ending WTA Finals.