Nogometni klub Osijek (), commonly referred to as NK Osijek or simply Osijek (), is a Croatian professional football club from Osijek. Founded in 1947, it was the club from Slavonia with the most seasons in the Yugoslav First League and, after the independence of Croatia in 1992, it is one of the four clubs that have never been relegated from the Croatian First League, the others being Dinamo Zagreb, Hajduk Split and Rijeka. History 1947–1976 The precursor to NK Osijek was founded on 27 February 1945 as NK Udarnik on the tradition of banned JŠK Slavija Osijek, which was founded in 1916 and played in the first jugoslav league 7 times between 1923 and 1941. Already in 1946, the club is merged with Jedinstvo, and changes its name to NK Slavonija. The conventional birthday of the club is considered to be the following year on the February 27, 1947, when NK Slavonija and Nk Bratstvo merge to form the FK Proleter. The first match played under that name comes the 16th of March of that same year, when Proleter beats city-rivals Mladost by five goals to nil. The first competition in which the club participated in was the Osječko Okružno Prvenstvo, along with four other teams. The club got into the second national league soon after. Proleter achieved placement into the Yugoslav First League in 1953, having won the so-called Croato-Slovenian League. The best players from that side were Andrija Vekić, Franjo Rupnik, Dionizije Dvornić and Franjo Majer. Proleter played in the First League for three seasons, but were then relegated to the second division. Proleter moved to current Gradski vrt stadium in autumn 1958 and changed its name to Slavonija as part of the unifying process of the boxing, athletics and Olympic lifting club in a newly founded sports association in 1962. It still plays in the second league. Five years later the association is disbanded and the club took on the name NK Osijek. The then-colours red and blue were switched to current colours blue and white. In 1970, Osijek wins the 2nd North League championship, however, Borac Banja Luka beat them in the promotion play-offs. A year later, Bijelo-plavi try for promotion again, winning in a penalty shoot-out against Rijeka, but end up being stopped by Vardar. The next time Osijek reached the promotion play-offs was in 1973. NK Osijek made it to the final round,