Hrvatski nogometni klub Hajduk Split, commonly referred to as Hajduk Split () or simply Hajduk, is a Croatian professional football club based in Split, that competes in the Croatian First League, the top tier in Croatian football. Since 1979, the club's home ground has been the 34,198-seater Stadion Poljud. The team's traditional home colours are white shirts with blue shorts and blue socks. The idea to form a football club was started by group of Split students who were studying in Prague. After observing a game between Slavia and Sparta Prague, the group gathered at the U Fleků tavern and talked of creating a football club at home. When they returned to Split, they put their plan in motion and Hajduk was founded on 13 February 1911. Between the early 1920s and 1940, Hajduk regularly participated in the Kingdom of Yugoslavia national championship. Following World War II and the formation of the Yugoslav league system in 1946, Hajduk went on to spend the entire SFR Yugoslavia period at the top level. Following the breakup of Yugoslavia, the club joined the Croatian First League in its inaugural season in 1992, never having been relegated from its top tier. Hajduk is thus the only ex-Yugoslav side to have never been relegated from the top flight since the foundation of the original Yugoslavia, though a number of ex-Yugoslav clubs have long spells in the top flight dating to the SFR Yugoslavia era. They are one of the most successful teams in Croatia and ex-Yugoslavia, having won nine Yugoslav and six Croatian league championships, in addition to nine Yugoslav and seven Croatian cup titles, and five Croatian supercup titles, without ever being relegated from its country's top football league. The club's golden era came in the 1970s, when they won four Yugoslav Leagues and five Yugoslav Cups. Hajduk is also the only club in Yugoslav football history that has won five-straight Yugoslav Cups (between 1972 and 1977), and also the only unbeaten champion (season 1950). Hajduk's biggest European achievements are appearances in three European Cup quarter-finals, one UEFA Cup semi-final and one Cup Winners' Cup semi-final. The club's main rivals are Dinamo Zagreb, with matches between the two referred to as the "Eternal Derby". Hajduk Split fans are called Torcida Split, who are the oldest organized firm in Europe, being founded in 1950. The inspiration of the name were the Brazilian fans at the