Australian Open PHOTOS: Federer, Azarenka cruise; Wozniacki knocked out

Roger Federer strolled nonchalantly into the fourth round of the Australian Open with a seemingly effortless 6-2, 6-2, 6-3 victory over Russia's Teymuraz Gabashvili on Rod Laver Arena on Saturday.

The 32-year-old Swiss, a four-time champion at Melbourne Park, had played his second round match against Blaz Kavcic on the second showcourt Hisense Arena on Thursday, the first time in 10 years he had played on the court.

Federer was at his clinical best on his return to Rod Laver, remaining unruffled even on the Russian's five break opportunities as he calmly swatted away the challenge in one hour, 41 minutes.

Federer will next meet either 10th-seeded Frenchman Jo-Wilfried or his compatriot Gilles Simon, who play later on Saturday.

Maria Sharapova continued her erratic Australian Open campaign with a scratchy 6-1, 7-6, (8-6) win over Alize Cornet that put her into the last 16 on Saturday but also sent her straight to the practice court in search of some sorely needed form.

Still rebuilding from a long layoff due to her troublesome right shoulder, Sharapova ran hot then cold against the 25th seeded Frenchwoman, her serve going awry in the hard-fought second set and only a late rally in the tiebreak saving the Russian from another potential marathon.

In her previous round, Sharapova had battled through the longest match of her career, a three-hour, 28-minute slug-fest against unseeded Italian Karin Knapp, played out on a 42 degrees Celsius (108 Fahrenheit) day.

Fatigue might have been a tempting excuse, but the Russian could hardly have used it, having felt fit enough to head back out on the court after a quick rest to iron out some worrying creases in her game.

"I just didn't have a great rhythm," Sharapova, seeded third, told reporters after bludgeoning 35 unforced errors and landing only half of her first serves.

"It's sometimes nice just to be able to come off the court and groove, just to get a good hit on the ball.

"I still feel like in certain situations I am a bit rusty and I'm not closing it out when I have to or maybe going for a little much or overthinking it a bit.

"That will come. I'm not worried about that. Those are the -- as long as I feel like I'm doing the right things and I'm playing the way I want to play, if I'm making those types of errors, they are going to go in eventually."

Sharapova's win over Cornet was her seventh match since pulling the plug on her 2013 season in August, but the 26-year-old has made hard work of her opening three matches at MelbournePark, where she won the 2008 title.

The loss of her once-potent serve since major surgery on her shoulder six years ago has long been her Achilles heel, and if her serve against Cornet was any indication, the old injury may still be weighing heavily.

Broken three times in the second set, the average pace of her first serves was 153 kph (95 mph) for the match, well down from her opening two rounds. Her second serve was also markedly slower.

Her decade-long tormentor Serena Williams, by contrast, has only been broken once and has been serving at an average just under 170 kph for the tournament.

Sharapova next plays Slovak 20th seed Dominika Cibulkova and has been spared a tougher run by a generous draw that offers eighth seed Jelena Jankovic as the highest seeded player before the semi-finals, where double defending champion Victoria Azarenka looms as the most likely opponent.

The Russian held out little hope of being completely free of the shoulder problems that have limited her to only one Grand Slam title win to the three prior to her major surgery.

"As I said, I think recovery for the rest of my career is going to be extremely important, making sure I do the right amount of work to the right amount of rest that I give it," she said. "But it's feeling good."

Grigor Dimitrov upset 11th seed Milos Raonic 6-3, 3-6, 6-4, 7-6(10) in a 156-minute Australian Open thriller on Saturday to reach the fourth round of a Grand Slam for the first time.

Famous more for being the boyfriend of Maria Sharapova, the 22nd ranked 22-year-old Bulgarian has long been identified as a rising talent in men's tennis but previously flattered to deceive on the game's biggest stages.

In the Margaret Court Arena bearpit on Saturday, though, he held his nerve through the tightest of fourth set tie-breaks to seal the victory on his fifth match point when Canadian Raonic netted a forehand.

The man once nicknamed "Baby Fed" for the similarity in his playing style to Roger Federer will next face world number 62 Roberto Bautista for a place in the quarter-finals after the Spaniard beat Benoit Paire 6-2, 6-1, 6-4.

Former World No 1 Caroline Wozniacki made an early exit from the Australian Open on Saturday with a 4-6, 7-5, 6-3 loss to rising Spanish talent Garbine Muguruza in the third round.

Dane Wozniacki, seeded 10th, appeared to be on course for a sixth appearance in the fourth round in seven visits to Melbourne Park when she wrapped up the first set in 39 minutes.

Venezuela-born Muguruza, however, arrived in Melbourne in good form after winning the warm-up tournament in Hobart as a qualifier and rallied to clinch the second set in just under an hour on Rod Laver Arena.

With both serves under pressure in the decider, the 20-year-old Spaniard converted all four of her break points to reach the fourth round of a grand slam for the first time.

Muguruza next meets fifth seed Agnieszka Radwanska of Poland.

An agitated Andy Murray was at his muttering, tormented best before reaching a higher plain to trounce Spaniard Feliciano Lopez 7-6 (7-2), 6-4, 6-2 and advance to the Australian Open fourth round on Saturday.

The scorching heat that plagued MelbournePark all week had given way to a pleasantly cool summer's day but the moody Briton fumed and berated himself throughout the opening two sets at Hisense Arena as he struggled with his backhand.

However, on surrendering the second set, 26th seed Lopez's resolve crumbled, allowing the 26-year-old Scot to coast to an encouraging victory in 135 minutes.

Fourth seed Murray, a three-times finalist at Melbourne Park, will next play French lucky loser Stephane Robert for a place in the quarter finals.

Victoria Azarenka remained on course for a third straight Australian Open title with a thumping 6-1, 6-0 victory over Yvonne Meusburger in exactly an hour on Saturday.

The second seed reached the fourth round when she broke the Austrian world number 49 for the seventh time with a thundering smash at the net to bring an end to a thoroughly one-sided contest on Rod Laver Arena.

Azarenka has not lost a set in her three matches this week and extended her winning streak at MelbournePark to 17 matches.

The Belarussian will next meet American Sloane Stephens, who she beat in controversial circumstances in the semi-finals last year on her way to her second successive Australian Open title.

France's Jo-Wilfried Tsonga raced into the last 16 of the Australian Open with a 7-6 (7-5), 6-4, 6-2 victory over Gilles Simon on Saturday, bringing an end to his compatriot's remarkable run at MelbournePark.

While a string of players dropped out early in the first week with niggling injuries in the sweltering conditions, the whippet-thin Simon earned the right to call himself one of the toughest men in tennis.

The 29-year-old badly twisted his right ankle at the Kooyong Classic exhibition tournament in the week before the year's first grand slam began and was hobbling around on crutches last weekend.

Given his game is built around his ability to scurry around the court to chase down the ball, Simon was seriously considering withdrawing from the tournament ahead of his first round clash with Germany's Daniel Brands.

In "really bad condition", he said he had been "at the limit" as to whether he could go on court but somehow overcame the pain in his ankle and temperatures exceeding 40 Celsius (102 Fahrenheit) to beat Brands in an epic five-set encounter.

The 18th seed had to come back from a two sets to one deficit, saved seven match points and finally beat Brands 16-14 in the fifth after more than four-and-a-half hours on court.

Simon's recovery was tested even further on Thursday when he was taken to another four hour, five-setter by Croatia's Marin Cilic in sweltering conditions to set up his clash with Tsonga.

Given his condition, Simon knew he had to go for broke against the sometimes slow-starting 10th seed but when Tsonga edged the first set tiebreak 7-5 the writing was on the wall.

Simon is never one to give up but Tsonga upped his game when necessary and sealed the victory when he whipped a forehand winner across the court from the tramlines after one hour and 53 minutes.

"It's always difficult when you play a friend, I've known him since we were nine or 10," said Tsonga, a 2008 finalist at Melbourne Park, who next meets sixth seed Roger Federer.

"It's like we create a little war."