From the records, it appears that football in Koper was played as early as in the 1920s, but officially, the club took the name NK Koper in 1955, when it was formed by the merger of two football teams: Aurora and Meduza. The club played under this name in different Yugoslav leagues until 1991 and was one of the most successful Slovenian clubs. After Slovenia became independent, the club started to play in the Slovenian PrvaLiga and Slovenian Second League. At the beginning of the 1990s, the club was achieving mid-table success. By the end of the 1990s, the club had been relegated to the second division twice, had serious financial problems and renamed itself to FC Koper, thereby avoiding the necessity of paying off its debts. With the advent of the new millennium, FC Koper consistently achieved positions in the upper half of the table (achieving third place in the 2001–02 season, its highest since Slovenian independence). In the 2003–04 season, they were playing in a European competition for the first time since 1991: the UEFA Intertoto Cup. Two years of mid-table anonymity and significant financial difficulties followed, in part because the former owner, Georg Suban, left substantial debts to the club and took half of the team with him when he moved to the other Slovenian PrvaLiga team Mura.