 His potential was proven to be great in the 1991 FIBA Europe Under-16 Championship, where Alvertis led the Greek team to the silver medal alongside Panagiotis Liadelis.At the same time, Panathinaikos was going through a transition period during which the lackluster team of the late 1980s strove to become a European powerhouse.Consequently, young Alvertis had to wait until the 1993–94 season to get significant playing time on a team with high ambitions, as PAO reached the EuroLeague Final Four.