MELBOURNE - The tactical brain of Andy Murray proved not to be a match for the brawn of Rafael Nadal in an electrifying fourth-round duel at the Australian Open on Monday.

In a battle between two of the young guns in the sport, second seed Nadal fought tooth-and-nail to down Murray 6-7 6-4 4-6 6-3 6-1.

Spain's Rafael Nadal and Andy Murray of Britain embrace after their match at the Australian Open tennis tournament in Melbourne January 23, 2007. [Reuters]

In the women's draw, there will be no room for sentiment after friends Martina Hingis and Kim Clijsters booked a tantalising quarter-final date.

Apart from being the youngest men left in the tournament, Murray and Nadal also shared the distinction of being the only players to have beaten world number one Roger Federer in 2006.

Facing each other across the net for the first time, Nadal had wished Murray "Good luck" before the warm-up. In hindsight, he may have wished he had kept his mouth shut.

Leading by a set and break in the second, Murray looked on the cusp of pulling off the biggest upset in the men's field.

Murray's tactics were clear from the outset - to employ an all out attacking strategy and to get Nadal out of his comfort zone on the baseline.

Hitting crisp volleys and sizzling groundstrokes, Murray gave his coach Brad Gilbert the thumbs up once he bagged the tight first set on a Hawk-eye overrule.

He maintained the blistering pace in the second to storm into a 4-1 lead but inexplicably lost his way.

The Spaniard pocketed the next five games to level the match and from then on the two men traded breakpoints and a breathtaking array of shots until Nadal finally flexed his bulging biceps to wear down an increasingly-frustrated Murray.

GREAT PLAYER

After almost four hours of drama, Nadal fell flat on his face having produced a ferocious running backhand winner to seal the contest.

"It was very, very tough," Nadal said courtside as he wiped the sweat off his forehead.

"Andy's a great player and he played with very good tactics. I needed a match like this (to go further)... I felt good physically in the fifth which was important," added the Spaniard, reaching the quarter-finals here for the first time.

Murray said: "I'm definitely not disappointed. I felt like I played a really great match and I played near to the best I can play right now."

While the Scot was burning the midnight oil until 1.51am local time, James Blake and David Nalbandian were catching a flight out of Melbourne.

A razor will be top of Blake's duty free shopping list after he lost out on a potential last-eight matchup against double French Open champion Nadal.

The American, who grows a beard whenever he is on a winning run, will be enjoying a close shave for the first time in over two weeks following his 7-5 6-4 7-6 defeat by 10th seed Fernando Gonzalez of Chile.

Argentine marathon man Nalbandian finally ran out of steam, wilting to a 4-6 6-3 6-2 6-3 defeat by Germany's Tommy Haas.

Nalbandian had already been on court for more than nine hours before Monday's contest which proved a bridge too far.

RESTORED CALM

In the women's draw, Maria Sharapova, Clijsters and Hingis restored calm at the Open a day after five women's seeds, including defending champion Amelie Mauresmo, were bounced out.

Three-times former champion Hingis withstood a fierce barrage from Li Na just as the Chinese looked set to become her country's first singles quarter-finalist at Melbourne Park.

Li held the upper hand for a set until she withered away under sunny skies to exit 4-6 6-3 6-0.

After fulfilling her side of the deal for a repeat of last year's quarter-final against Clijsters, the Swiss had a message for her friend.

"Kim better win, I'll be waiting, I'll be watching," she said courtside.

Clijsters duly obliged.

The Belgian had proved to be a roadblock for Daniela Hantuchova on eight previous occasions and the slender Slovakian again found the title favourite an impenetrable obstacle.

Clijsters romped to a 6-1 7-5 win in 79 minutes after a wild crosscourt error sealed Hantuchova's fate.

"It's always a pleasure to play against her (Hingis), she's such a great champion," said Clijsters."

Fans scrambled for their earplugs on Rod Laver Arena as top seed Sharapova shrieked to a 7-5 6-4 win in a Russian catfight against Vera Zvonareva. She will next run into another compatriot, Anna Chakvetadze.

Third seed Nikolay Davydenko will be hoping his run to the latter stages here will give him the exposure he needs to secure a long-overdue clothing sponsor. The only man in the top 10 without a shirt deal, he gave Czech Tomas Berdych a 5-7 6-4 6-1 7-6 dressing-down.