 Amoroso played for Málaga during the 2004–05 season, although he was mainly used as a substitute, scoring only 5 goals in 29 appearances, as Málaga finished the season in 10th place in the league.Amoroso moved to São Paulo in the summer of 2005 and immediately helped them to the Copa Libertadores, the most prestigious club prize in South America.In January 2006, after having won the FIFA Club World Championship, finishing the tournament as top scorer, he returned to Italy, signing an 18-month contract for A.C. Milan as a replacement for Christian Vieri, who had transferred to Monaco.