Rafa Nadal overpowered 18-year-old local hope Bernard Tomic 6-2, 7-5, 6-3 to book his spot in the last 16 of the Australian Open on Saturday.

The world number one, bidding to become only the third man, and the first since 1969, to hold all four grand slam titles at once, was given a real workout by the teenager under the floodlights.

Nadal, Melbourne champion in 2009, bombed through the first set, but Tomic came out swinging in the second, bursting into a 4-0 lead before the swashbuckling Spaniard came roaring back.

Red T-shirt drenched in sweat, Nadal finally took the second set 7-5 with a fierce serve down the middle and after an early break in the third, closed out the match with a drilled backhand which was too hot for Tomic to handle.

A razor-sharp Andy Murray pulverised Spain's Guillermo Garcia-Lopez 6-1, 6-1, 6-2 to sweep into the last 16 of the Australian Open on Saturday while being serenaded in bright sunshine.

The fifth seed, beaten by Roger Federer in last year's Melbourne final, completed the rout with a viciously whipped forehand into the corner after just one hour and 22 minutes.

"It was a perfect match in many ways," Murray said after a performance underlining his credentials for a first Grand Slam title.

"Obviously it was pretty hot, so it was nice to get off court as quickly as possible," added the Briton. "It was over quickly. I didn't use up much energy at all."

Murray, roared on by a boisterous fan club singing popular children's nursery rhymes adapted for the player, went two sets up on a sun-baked Rod Laver Arena after just 52 minutes.

It was majestic tennis from Murray, who suddenly snapped into gear after losing the first three points of the third round match.

Garcia-Lopez stunned the 23-year-old Scot with a between-the-legs wonder shot on the second point, but by the second set the tormented Spaniard was belting balls skyward in frustration.

"It was the first time someone passed me on a through-the-legs shot on the tour," said Murray with a sheepish grin. "It was good, very close one on the line."

The third set followed the same pattern, with a dominant Murray in no mood to hang about in the energy-sapping heat and his opponent also looking keen to retreat to the safety of the locker room.

Murray next faces the winner of the evening match between 11th seed Juergen Melzer of Austria and Cypriot Marcos Baghdatis, an Australian Open runner-up in 2006.

Fourth seed Robin Soderling eased effortlessly into the last 16 of the Australian Open with a methodical 6-3, 6-1, 6-4 trouncing of Czech qualifier Jan Hernych on Saturday.

The Swede racked up 33 winners in the bright sunshine on the Hisense Arena, and it was only repairs to a dead spot discovered on the court at the start of the third set that extended the contest to nearly two hours.

The oldest man left in the tournament, 31-year-old Hernych was playing in the third round of a Grand Slam for the first time in 19 attempts.

The world number 241 showed some pride with a gallant rearguard action in the third set but Soderling rarely needed to move out of first gear to keep intact his unbeaten record in 2011.

"Physically I feel very good," he told reporters. "I haven't spent too many hours on court yet and I'm already in the fourth round, which is very good.

"So I think for me it's a little bit of an advantage."

World number two Vera Zvonareva nervously threw away three service breaks but finally closed out a 6-3, 7-6 victory over Lucie Safarova to advance to the fourth round of the Australian Open on Saturday.

Zvonareva broke early in each set and was cruising to victory at 4-2 in the second, but double-faulted to allow 31 seed Safarova to break back to 4-4 at a sun-drenched Rod Laver Arena.

The Russian wobbled twice more when serving for the match to allow Safarova into a tiebreaker, much to the delight of the Czech 23-year-old's boyfriend and Wimbledon finalist Tomas Berdych watching from the stand.

Safarova saved two match points but conceded the third after Zvonareva deftly lobbed her to close out a pulsating tiebreak 11-9.

Third seed Kim Clijsters survived her first test of the Australian Open to beat Frenchwoman Alize Cornet 7-6, 6-3 and advance to the last 16 on Saturday.

The Belgian, a three-times Grand Slam winner and Melbourne runner-up in 2004, struggled to impose herself in the first set on Cornet, celebrating her 21st birthday on a sweltering Rod Laver Arena.

The former world number one's experience showed in the tie-break which Clijsters took 7-3 before normal service resumed in the second set as she found the range with her heavy groundstrokes.

Clijsters squandered two match points on Cornet's serve at 5-2 but moments later it was all over, a deep second serve out wide sealing victory in an hour and 31 minutes.

Petra Kvitova shattered Australia's hopes of a first women's champion in their home event since 1978 by knocking out fifth seed Sam Stosur 7-6, 6-3 to advance to the fourth round of the Australian Open on Saturday.

The 28th-seeded Czech silenced the fiercely parochial crowd at Rod Laver Arena by slapping a forehand winner from the baseline to clinch the first set tiebreaker 7-5, before taking a decisive break at 3-2 in the second set.

Stosur, her confidence plummeting, slapped a forehand wide to concede three match points then watched helplessly as the ice-cool Kvitova guided a forehand volley down the line to seal the match in 95 minutes.

"I liked the big court and crowd here, unfortunately it was against me," the 20-year-old Kvitova laughed in a courtside interview.

She will next play Italy's Flavia Pennetta.