Men's seeds advance while top women continue to struggle at the Australian Open

Spanish third seed Garbine Muguruza has joined the ever-growing list of top ranked women to crash out of the Australian Open's first week, while the men continued on course on Saturday.

Despite rain again threatening play in Melbourne, the worst of the weather passed in the early morning; unfortunately for Muguruza the day was just as dark even without looming thunderclouds.

She was sensationally upset by Czech veteran Barbora Strycova 6-3, 6-2 in just over an hour and joins second seed Simona Halep, sixth seed Petra Kvitva, eighth seed Venus Williams and ninth seed Karolina Pliskova as top 10 casualties at the open.

Muguruza said she felt like her opponent was dictating the play too well, and was never in the match.

"I felt like I had not so much energy, that's for sure," Muguruza said in her press conference.

"I felt I was not moving very well. I guess also Barbora was making me move - she was being smart."

Strycova moves on to play two-time Australian Open champion Victoria Azarenka, who - incidentally - has knocked the Czech woman out of the tournament twice - in both 2014 and 2015.

Azarenka was relentless against Japanese qualifier Naomi Osaka, losing just two games in the 6-1, 6-1 win.

Through the first three rounds, the Belorussian has lost just five games out of 41 played, but refused to say she was in career best form when posed the question in her press conference.

"The score doesn't really tell the whole story sometimes," she said, shaking off the question.

"But I'm pretty happy with the way I'm playing. I want to still keep improving from match to match, because it's only getting harder from here."

Meanwhile men's dark horse Milos Raonic continued his unbeaten start to 2016, taking care of Viktor Troicki 6-2, 6-3, 6-4.

Cruising through the first two sets, the Canadian was challenged in the third; Troicki handed Raonic just his first broken service game all tournament, but the No. 13 seed managed to break back - and then again - to close out the match in straight sets.

Raonic will have a tough time advancing to the final 8 however, with the No. 4 seed - and two-time Grand Slam winner - Stan Wawrinka standing in his way. Despite the challenge, Raonic said he has the potential to beat the 2014 Australian Open champ.

"(Wawrinka's) playing well, he has played solidly through his first three matches," Raonic said in his press conference.

"I have it within myself to find the solution, but the question is 'can I step up and do it?' so we'll see."

Wawrinka was on-court for just under two hours in his straight sets win over Lukas Rosol, but admitted post-match he had been suffering a "little cold" throughout the first week.

Despite his lingering sickness, the Swiss said he was in good form heading into the second week of the tournament.

"I was moving well, returning well and I love (Rod Laver Arena)," he said after the match. "I'm happy to my start of the year."

Also on Saturday, big-serving 10th seed John Isner shook off a challenge from Spanish No. 18 seed Feliciano Lopez to win in four sets, David Ferrer cruised into his sixth straight last-16 berth at Melbourne Park, while No. 7 seed Angelique Kerber continues to buck the trend of top seeds falling early, winning her way to the fourth round 6-1, 6-3 over the USA's Madison Brengle. Endit