Andy Murray saw off a tricky challenge in the form of Sam Querrey in straight sets to set up a last 16 clash with Mischa Zverev. Photograph: (AFP)
In the women's section, defending champion Angelique Kerber finally came into her own as she beat Kristyna Pliskova in straight sets
Andy Murray saw off giant-killer Sam Querrey on Friday as he ramped up his bid for a first Australian Open title after the shock departure of six-time champion Novak Djokovic.
On a cool day in Melbourne, the men's number one and women's top seed Angelique Kerber both hit a hot patch of form as the final rounds beckoned.
Murray will have watched from the sidelines as second seed Djokovic, his conqueror in four Melbourne finals, suffered a stunning defeat to 117th-ranked Denis Istomin on Thursday.
Querrey also upset Djokovic at Wimbledon last year but Murray, made a knight in Britain's New Year honours, never looked like slipping on any banana skins in round three.
He put Querrey away 6-4, 6-2, 6-4 in just under two hours, winning 77 percent of points on his first serve and facing only three break points in a clinical display.
The Scot also showed no signs of discomfort in his right ankle, after he rolled it painfully during his second-round win over Andrey Rublev.
"I felt better and better as the match went on in terms of my movement," he said. "The ankle was a little sore and I was a little tentative at the start but it got better and better through the match."
Murray bats for Djokovic
Andy Murray on Friday downplayed Novak Djokovic's shock exit from the Australian Open and said it was "unreasonable" to expect to the Serb to maintain his dominance long-term.
The top seed was as surprised as anyone by Djokovic's defeat to 117th-ranked Denis Istomin in the second round, but he dismissed suggestions his rival was "struggling".
"I mean, struggling by the highest standards," Murray said, after he beat Sam Querrey 6-4, 6-2, 6-4 to reach the fourth round.
Next up for Murray is an assignment with Mischa Zverev, the elder brother of highly-rated German teen Alexander who came through in four sets against Tunisia's Malek Jaziri.
The winner of that meeting will play either Roger Federer or Tomas Berdych, the old Grand Slam rivals who play the night match on Rod Laver Arena later.
Stan through to next round
Stan Wawrinka, the 2014 champion, survived a four-set tussle with Viktor Troicki 3-6, 6-2, 6-2, 7-6 (9/7) and now faces Italy's Andreas Seppi, who ousted Steve Darcis of Belgium.
Former finalist Jo-Wilfried Tsonga also came through in four sets against American Jack Sock and will play Briton Dan Evans, who beat Australia's Bernard Tomic 7-5, 7-6 (7/2), 7-6 (7/3).
In the women's draw, Kerber finally got into her stride with a 6-0, 6-4 destruction of Kristyna Pliskova, the 58th-ranked twin sister of Czech fifth seed Karolina.
The German defending champion was an early loser at both of her warm-up tournaments and was taken to three sets in unconvincing wins in round one and two.
But Kerber clicked into gear against Pliskova, winning in just 55 minutes to set up a last-16 clash with America's Coco Vandeweghe, who ousted Canadian starlet Eugenie Bouchard.
"I'm looking forward to the next one. Yeah, I think that I find my rhythm to the tournament now," Kerber said.
Svetlana Kuznetsova outlasted fellow veteran Jelena Jankovic 6-4, 5-7, 9-7 and will next play fellow Russian Anastasia Pavlyuchenkova.
Venus Williams beat Duan Yingying 6-1, 6-0 to end Chinese involvement, earning a fourth-round match against German qualifier Mona Barthel, who overcame Australia's Ashleigh Barty in three sets.