Macijauskas joined the Spanish League club Tau Ceramica, for the next two seasons and he helped them win a Spanish Cup title in 2004. On 17 December 2003 he scored a career-high 40 points, in a EuroLeague 2003–04 season game against the French League club ASVEL Lyon. With Tau Ceramica, he also reached the EuroLeague's Final in 2005, where his team lost to the Israeli Super League club Maccabi Tel Aviv; which was also led by a Lithuanian player, and EuroLeague Final Four MVP, Šarūnas Jasikevičius. Macijauskas was selected to the All-EuroLeague First Team of the 2004–05 season. In two seasons with Tau, he played in 42 EuroLeague games, in which he averaged 18.6 points, 2.4 rebounds, and 2.5 assists per game.
