Samoa claimed their greatest ever victory with a stunning 32-23 upset of Australia at the Sydney Olympic stadium on Sunday on a humiliating afternoon for the two-time World Cup winners. Rugby's second-ranked team were outplayed by the big-hearted Samoans just a week away from the Wallabies' Tri-Nations opener with South Africa and only months before the World Cup in New Zealand. The Samoans swarmed all over the hosts, outscoring them four tries to two for their first win over Australia in five meetings. Tenth-ranked Samoa ambushed the Australians with a 17-0 lead inside the opening half-hour and although the Wallabies pulled back to trail 17-13 minutes after half-time, that was as close as they got. Samoa got off to a flyer when Leicester Tigers winger Alesana Tuilaga raced 70 metres to score off a turnover. The powerful Tuilaga beat off Matt Giteau's tackle to score in the 11th minute and crowned his runaway try with an extravagant swan dive in-goal. Tusi Pisi added the conversion to his earlier penalty goal to give the Pacific Islanders a 10-0 lead. Australia were shell-shocked. The Wallabies passed up a possible 12 points by electing to run the ball from four penalties in the opening 20 minutes, but Giteau was forced to take a 45m penalty attempt, which he missed. The Samoans continued to pressure the home side and were rewarded when debutant scrumhalf Nick Phipps had his clearing kick charged down for fullback Paul Williams to score in the 29th minute. Pisi's conversion gave Samoa a stunning 17-0 lead. South African referee Marius Jonker lost patience with Samoa and lock Daniel Leo was yellow carded for hands in the ruck. The Wallabies used their superior numbers in the scrum to position winger Digby Ioane to score a converted try two minutes before halftime. Giteau reduced the deficit to seven points with a penalty on the half-time siren for the Wallabies to trail 17-10. The Australians edged closer just after the resumption with Giteau's second penalty, but Samoa again rocked the home side with their third try minutes later. Samoa kept the ball alive and number eight George Stowers sent lock Kane Thompson charging over wide out for a 22-13 lead. The Wallabies fell further behind when Phipps and Adam Ashley-Cooper fumbled Tuilagi's kick for centre George Pisi to ground the ball over the try-line under a mass of bodies. Brother Tusi converted to extend the lead to 29-13 as concerned Wallabies' coach Robbie Deans sent on star backs Will Genia and Kurtley Beale as reinforcements with the game heading into the last quarter. Tusi Pisi kept Samoa in control with a 66th-minute penalty before Giteau gave the Australians some hope with a try out wide after a kick and regather from replacement forward Scott Higginbotham. But the hard-working Samoans held on in the rain and rejoiced wildly as the full-time siren sounded to register their biggest rugby achievement. The Wallabies had a desperately fought 9-3 win over Samoa in their first meeting at the 1991 World Cup in Pontypool, but won more comfortably in their other three Tests, including 73-3 in 1994 and 74-7 in 2005, both in Sydney.