The Chinese side, making their debut in the tournament, scored their Group F victory with second-half goals from Honduran striker Luis Ramirez and substitute Ba Li at the Yellow Dragon Stadium on Tuesday.
"They were tired and they didn't know much about us," Wu told reporters of Hangzhou's opponents. "Chinese players are physically stronger than other East Asian rivals.
"I always encouraged my players to give full play to our physical strength and height."
Chinese Super League runners-up Tianjin Teda were also celebrating on Tuesday after they claimed a 1-0 away win over South Korean side Jeju United in the opening match of the 2011 tournament.
The Koreans controlled the Group E match for long periods at a windy Jeju World Cup Stadium but without Asian Cup top scorer Koo Ja-cheol, who moved to German side VfL Wolfsburg recently, they struggled in front of goal.
Lee Sang-hyub hit the crossbar in stoppage-time but Jeju could not find an equaliser for Yu Dabao's 55th minute effort.
"The ability of Chinese teams has improved a lot and I hope that this result helps to show that," Tianjin coach Arie Haan told reporters.
Saudi Arabia's Al Hilal were also victims of a surprise opening day defeat when they lost 2-1 at home to Iranians Sepahan in Group A.
The night's biggest winners were 2008 champions Gamba Osaka, who thrashed Melbourne Victory 5-1 after some woeful defending from the Australians saw them go 3-0 down after just 11 minutes.
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