MELBOURNE, Australia (AP) -- Two-time defending champion Victoria Azarenka made it all look routine Saturday in defeating unseeded Yvonne Meusburger 6-1, 6-0 in a third-round match at the Australian Open.
Azarenka broke Meusburger's serve twice in the first four games and was rarely troubled in exactly one hour to advance to a fourth-round match against American Sloane Stephens.
Last year, Azarenka beat Stephens in the semifinals at Melbourne Park under acrimonious circumstances when Azarenka took a questionable medical time out while trailing Stephens. When Azarenka returned, she broke Stephens' serve and went on to win the match.
"Sloane is a great player, she's improved so much from last year," Azarenka said Saturday.
Earlier, the girlfriend and boyfriend pair of Maria Sharapova and Grigor Dimitrov both advanced along with Wimbledon champion Andy Murray and 17-time Grand Slam winner Roger Federer.
And finally, the oppressive heat wave of the past four days gave way to more benign conditions.
Sharapova, who endured the worst of the torrid heat in her second-round match, beat Alize Cornet 6-1, 7-6 (6) to reach the fourth round. The match was played in high humidity but in temperatures of about 22 Celsius (72 Fahrenheit), considerably cooler than the scorching 42 C (108 F) conditions she endured for 3 hours, 28 minutes in her second-round win on Thursday.
Dimitrov reached the second week at a major for the first time when he converted his fifth match point to beat No. 11-seeded Milos Raonic of Canada 6-3, 3-6, 6-4, 7-6 (10).
The 22-year-old Bulgarian is considered one of the up-and-coming players on the men's tour, as is Raonic. At the end of the match, the two hugged like old mates at the net.
"I think it's a great stepping stone for me to get into that second week," Dimitrov said. "But I have practiced a lot. I have done a lot of homework. So, to me, in a way it's a bit expected."
Dimitrov will next play Roberto Bautista Agut, who followed his upset second-round win over No. 5 Juan Martin del Potro with a 6-2, 6-1, 6-4 win over No. 27 Benoit Paire.
Federer had a 6-2, 6-2, 6-3 win over Teymuraz Gabashvili, and three-time finalist Murray reached the fourth round for the sixth straight year with a 7-6 (2), 6-4, 6-2 win over No. 26-seeded Feliciano Lopez.
In completed night matches, 2008 finalist Jo-Wilfried Tsonga beat fellow Frenchman Gilles Simon 7-6 (5), 6-4, 6-2 and No. 16 Kei Nishikori had an equally easy time beating Donald Young, the last American man in the singles draw, 7-5, 6-1, 6-0.
Tsonga next plays Federer, who is No. 6 at this Australian Open, his lowest seeding in more than a decade, after a year in which he didn't reach a Grand Slam final for the first time since 2002.
Last year, Federer beat Tsonga in the quarterfinals here.
"For me it's going to be the possibility to have revenge," Tsonga said.
Murray, playing only his second tournament since minor back surgery in September, was only broken once in a 2-hour, 15-minute match and next faces Stefane Robert, a lucky loser from qualifying, who is into the fourth round for the first time after beating Martin Klizan.
"It's been a good start," Murray said. "It was very tricky the first couple of matches with the heat, but today was beautiful to play in."
Sharapova will next play Dominika Cibulkova, who beat No. 16 Carla Suarez Navarro 6-1, 6-0 in 59 minutes. Former No. 1-ranked Jelena Jankovic had a 6-4,7-5 win over Kurumi Nara, her third consecutive victory over a Japanese player.
Fifth-seeded Agnieszka Radwanska had a 5-7, 6-2, 6-2 over No. 29 Anastasia Pavlyuchenkova and will next play Garbine Muguruza of Spain, who beat former No. 1-ranked Caroline Wozniacki 4-6, 7-5, 6-3.
No. 13 Stephens, who had an upset win over Serena Williams in the quarterfinals here last year, reached the fourth round at a fifth consecutive major with a 7-5, 6-4 win over Elina Svitolina of Ukraine and a date with Azarenka.
Williams will play her fourth-round match Sunday against former French Open champion Ana Ivanovic. Three-time defending champion Novak Djokovic plays Fabio Fognini, also in an afternoon match on Rod Laver Arena.