Nadal cruises

The Spaniard was leading 6-4 3-0 when Frenchman Mathieu, who earlier had treatment on a leg injury, was forced to quit.

Nadal will play Jarkko Nieminen, the 24th seed, in the quarter-finals after the Finn dispatched Andy Roddick's conqueror Philipp Kohlschreiber 3-6 7-6 (7) 7-6 (9) 6-3.

Argentina's David Nalbandian joined the list of top seeds knocked out of the third round when he suffered a 6-1 6-2 6-3 loss at the hands of former world number one Juan Carlos Ferrero.

Nalbandian, who had suffered muscle spasms in his back the week prior to the tournament, was continually harassed by the Spanish baseliner, chasing down virtually every shot the 10th-seed attempted.

Ferrero, a finalist in Auckland last week, converted six of his 10 break opportunities and gave Nalbandian one chance, which he was unable to convert.

The match had been postponed from Saturday due to rain and the delay seemed to have hampered the Argentine, who followed women's second seed Svetlana Kuznetsova and sixth seed Anna Chakvetadze as third round casualties.

Ferrero will next meet Spanish compatriot David Ferrer after the fifth seed eased past American Vincent Spadea 6-3 6-3 6-2.

Another top seed was ousted by the run of flamboyant Frenchman Jo-Wilfried Tsonga, as the man who stunned British ninth seed Andy Murray in the first round of the tournament eliminated the hopes of eighth seeded compatriot Richard Gasquet 6-2 6-7 7-6 6-3.

Tsonga fired in 18 aces and hit 75 winners to reach his first-ever Grand Slam quarter-final in stylish fashion.

The Frenchman will now face 14th seeded Russian Mikhail Youzhny , who also pulled of an impressive fourth-round upset in beating fourth seeded compatriot Nikolay Davydenko 7-6 6-3 6-1.

It is the first time in four tries that Youzhny beat his number one ranked countryman and also the first time in four seasons that Davydenko failed to reach the last eight in Melbourne.