According to some sources, Colceag was born in southern Bessarabia (Budjak), at a time when Moldavia was a vassal state to the Ottoman Empire. He entered the Ottoman army and was first posted in Bosnia. Here, he converted to Islam and took the name of "Hussein". He distinguished himself during the Russo-Turkish War of 1710–1711, being promoted bölükbaşı. In 1717 Sultan Ahmed III awarded him the title of pasha and named him commander of Khotyn Fortress. Colceag kept this position for 22 years. In Turkish historiography he is also known as Kolchak-Pasha. In 1734 (according to other sources 1736) he was appointed vizier, but held this position only for a short time.