The Portugal international midfield player has joined in a €500,000 deal which also sees Porto players Júnior and Bruno Alves move on loan to Guimarães next season.
Mendes, who has put pen to paper on a four-year contract, said: "This is a dream come true." The 24-year-old enjoyed his most successful season in 2002/03. As well as helping Guimarães to fifth place in the Super Liga, he won his first international caps against Scotland and Italy.
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