Sankovich made his first Belarusian team, as an 18-year-old, at the 2008 Summer Olympics in Beijing, competing in both the 100 m backstroke and the medley relay. Leading up to the Games, he broke a Belarusian record and cleared a FINA B-cut of 56.10 at the Belarusian National Championships in Minsk. In the 100 m backstroke, Sankovich came second in his heat behind Colombia's Omar Pinzón by 0.28 of a second with 55.39 seconds, but failed to advance to the semifinals, finishing twenty-ninth out of 45 entrants in the prelims. Few days later, he joined with Yauheni Lazuka, Viktar Vabishchevich, and two-time Olympian Stanislau Neviarouski for the men's 4 × 100 m medley relay. Swimming the backstroke leg, Sankovich recorded a time of 55.11 seconds, and the Belarusian team went on to finish the heats in sixteenth place, for a total time of 3:39.39.