The LOTTO Ekstraklasa is a Polish professional league for association football clubs. At the top of the Polish football league system, it is the country's primary football competition. It is contested by 16 clubs, operating a system of promotion and relegation with the I liga. The Ekstraklasa season starts in late July, and ends in May or June the following year, teams play a total of 37 games each. The Ekstraklasa (former I liga) was officially formed as Liga Pi?ki No?nej on 1 March 1927 in Warsaw, but Polish Championships and the Polish Football Federation PZPN (Polski Zwi?zek Pi?ki No?nej) had been in existence since 20 December 1919, a year after the independence of Poland in 1918. The first games of the freshly created league took place on 3 April 1927, while first national non-league football championship took place in 1921. First, historic champion of the newly restored Second Polish Republic was Cracovia, after which Pogon Lwow was the champion in 1922, 1923, 1925 and 1926.