In 1998, Hasan signed with Galatasaray for $4.4 million, but almost immediately upon arrival, he was suspended from football for six months after doping testing returned a positive result for the banned substance Phenylpropanolamine. The winger did not allow the sizable bout with adversity to ruin his burgeoning career, as he roundly regained his spot with Galatasaray in the 1999–2000 season, in which the club won the first major European trophy for any Turkish club. Galatasaray won the UEFA Cup title in 2000 over Arsenal in a hard-fought final, and went on to win the 2000 UEFA Super Cup.