On the fifth day of the Australian Open warmup, defending champion Roger Federer finally opened his season at the Brisbane International and dispatched German qualifier Tobias Kamke 6-2, 6-1.

Federer advanced to a quarterfinal against Grigor Dimitrov, who beat Viktor Troicki 5-7, 7-6 (6), 6-2 earlier Thursday.

The 17-time major winner converted five of his six breakpoint chances and saved the only one he faced, finding his touch quickly in his first competitive match of 2016, and dispelling pre-match rumors that he might be carrying an injury.

Milos Raonic, last year's runner-up, was also back in action for the first time this season, and defeated Croatia's Ivan Dodig 6-7 (2), 6-1, 6-4. He set up a quarterfinal against Lucas Pouille, who upset sixth-seeded David Goffin 7-6 (5), 4-6, 6-3.

While the top-ranked women have succumbed to injuries or inconsistency in the first week of the season, Victoria Azarenka has maintained her surge in form.

The two-time Australian Open champion reached the Brisbane International semifinals by beating eighth-seeded Roberta Vinci 6-1, 6-2.

She has dropped just 10 games en route to the semis, where she'll meet Samantha Crawford, the No. 142-ranked U.S. qualifier who beat Andrea Pektovic 6-3, 6-0.

Azarenka, who was limited to 23 tournaments across the last two seasons due to foot and leg injuries, was broken once in each set but converted seven of her 11 breakpoint chances against Vinci, who ended Serena Williams' bid for a true Grand Slam in the U.S. Open semifinals.

''I really had to take control in my own hands, because she comes up with some really difficult situations and combinations which keep you on your toes,'' Azarenka said.

She added that while she didn't know a lot about Crawford, ''Obviously nobody is getting into semifinals by not playing well.''

Fourth-seeded Angelique Kerber, the highest-ranked woman remaining in Brisbane, advanced past Anastasia Pavlyuchenkova 6-4, 6-4, and will next play No. 6-seeded Carla Suarez Navarro, who held off Varvara Lepchenko 4-6, 6-4, 7-5.

At the ASB Classic in Auckland, New Zealand, third-seeded Caroline Wozniacki moved into the semifinals with a 6-1, 6-0 win over Alexandra Dalgheru.

''I really hit it well, I went for my shots,'' said Wozniacki, who made only eight unforced errors. ''I came to the net - I didn't even know I could volley like that, so I was pleasantly surprised.''

Wozniacki has a 5-0 record against her semifinal opponent, Sloane Stephens. The fifth-seeded American beat qualifier Naomi Broady of Britain 7-6 (6), 6-3.

Earlier, Tamira Paszek beat fellow qualifier Kirsten Flipkens 6-4, 6-7 (3), 6-3 in a match that lasted almost three hours.

Paszek's semifinal opponent will be Julia Goerges, who outlasted Nao Hibino of Japan 6-7 (3), 6-2, 6-4.

At the Hopman Cup in Perth, Ukraine qualified for Saturday's final with singles wins over the Australia Gold team of Jarmila Wolfe and Lleyton Hewitt.

Wolfe lost her singles to Elina Svitolina 6-3, 6-3 and former No. 1-ranked Hewitt, who will retire after the Australian Open in two weeks, fell 4-6, 6-3, 6-4 to Alexandr Dogopolov to give Ukraine an insurmountable 2-0 lead. Australia won the mixed doubles 3-6, 7-5, 10-5.

In a night match, Jack Sock and Vicky Duval were to play for the United States against the Czech Republic in a matchup between teams already eliminated. Duval replaced Serena Williams, who has inflammation in her left knee and wants to rest ahead of the Australian Open beginning in 11 days.

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