 In 1924 BSK brought the first foreign professional footballers when they brought Rudolf Wetzer and Dezideriu Laki from Romania.By the end of the 1930s the political tensions and rivalry between Serbs and Croats within the Kingdom of Yugoslavia reached its peak, and this was also reflected in football with the creation of two separate leagues in 1939, the Serbian one, and the Croatian-Slovenian, with the top classified teams in both of them qualifying to a national final stage to decide the national champion.However, in the following season, Slovenia separated and formed its own league, thus having now three leagues, Croatian, Serbian and Slovenian, which would serve as qualifying leagues to the final stage where the national champion would be decided.