The 2002–03 season, Tomasson's first at Milan, saw them winning the Italian Cup. Tomasson was most often used as a late substitute, but did manage to score three goals in the UEFA Champions League; and thereby also held his share of the trophy, when Milan won the prestigious tournament in May 2003. Tomasson missed the final because of an injury that he picked up in the first leg of the 2003 Coppa Italia Final. During the 2003–04 season, Tomasson was given more playing time and managed to score 12 Serie A goals in a title-winning campaign. In August 2004, he was also a part of the Milan team that won the Italian Super Cup, with a 3–0 victory against the Coppa Italia champions Lazio.