During this period the club got nicknamed in the press as the "Provincial Uruguay".Provincial because they were playing in the Provincial Group of the Belgrade Subassociation League, and Uruguay because of their playing style which resembled Uruguay´s one which was highly regarded at that time as they were the Olympic champions. The nickname was used for the first time in 1927. By early spring of 1928, Mačva finished top of the First League of the Novi Sad Distict where they beat their main rivals Vojvodina. In the decisive match Mačva won Vojvodina by 6:1. By the league system of that time, the winners of thr district (župa) leagues had to compete between them to determine the Belgrade Subassociation Provincial League champion. Mačva first played at home against the winner of Banat district league champion, Obilić Veliki Bečkerek, which they won by 4:1, and then played away and won by 4:3 the champion of the Šumadija distict league, FK Šumadija 1903. Then, the drew determined that the final match will be played in Šabac against ZAŠK from Zemun, which Mačva smashed by 6:1 with goals by Bora Kesić, Milan Perić, Raduška Gajić and Kokan Stevanović.
After becoming Belgrade Subassociation Provincial League champions, Mačva became notorious and the main daily newspaper Politika consistently used the nickname Provincial Uruguay specially after their surprising win against SK Jedinstvo Beograd by 3:2 in Belgrade, and after their successful tour in Greece where they beat Thessaloniki sides Iraklis by 3:1, and Aris by 4:2.
In the following season they became Novi Sad District League champions for the third time and qualified for the Vojvodina Group of the Belgrade Subassociation League. Mačva wins the league and thus earns a spot in the Yugoslav First League where competes among the major clubs in the country. They make great performances against BSK Belgrade and Hajduk Split and win the 3-time Yugoslav champions Građanski Zagreb. Mačva players start to receive calls for the Yugoslav national team, namely Milorad Arsenijević, Ivan Bek, Milorad Ilić, Milanče Jovanović, Radomir Vojisavljević, Andreja Kojić and Bora Kesić. Other players of the Provincial Uruguay generation were Jefta Jovanović, Jovan Vračarić, Jovan Cvetković, Gidra Šljivić, Milan Perić, Kokan Stefanović, Kulja Suvajdžić, Bata Kiš, Vido Božović, Moma Jovanović, Mikica Sinđelić, Đole Jovanović, Đorđe Pantazijević, Raduška Gajić, Mikela Stanojčić, Mita Salajdžijević, Nikola Kradžić, Brana Janković and others.