Sporting midfielder Luis Filipe became the first player to score at the 52,000-capacity Alvalade XXI stadium when he ran into the box in the 26th minute to pick up a long-range cross from team mate Rui Jorge on the left and beat Fabien Barthez.
As Sporting continued to dominate, captain Beto Severo was unlucky not to score when he forced Barthez into a spectacular flying save ten minutes from the break as United's defence looked vulnerable.
New signing Djemba Djemba had the only real chance for a lacklustre United in the first half when he beat Sporting goalkeeper Ricardo Pereira from 20 metres but saw the ball go agonisingly wide of the right post.
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Clearly missing Ryan Giggs and Roy Keane, the English champions fell further behind last season's third place Portuguese team in the 62nd minute.
Former Portuguese international Joao Pinto put the Lisbon side 2-0 ahead when he beat Mikael Silvestre in the air to glance in a free kick from Brazilian team mate Fabio Rochemback.
In the hope of salvaging some pride Manchester United manager Alex Ferguson decided to bring on striker Ruud van Nistlerooy with 20 minutes remaining, but Pinto added to the visitors' humiliation by making it 3-0 in the 80th minute.
Cristiano Ronaldo crossed a ball from the right into the penalty area, which Luis Lourenco flicked backwards into the path of an unmarked Pinto whose shot bounced in off the post.
The visitors were gifted a consolation goal three minutes from the whistle, however, as Sporting's Hugo Vieira tried to clear a cross from Ole Gunnar Solskjaer but only managed in slicing the ball into his own net.
The new Alvalade XXI stadium in Lisbon will stage four group stage games and one of the Euro 2004 semi-finals.
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