On December 4, 2015, Mazdzer won the 2015–16 Luge World Cup Men's singles event at Lake Placid in the first-ever one-two finish for the United States in a men's singles luge World Cup event, with the 2014–15 winner and track record holder, Tucker West, coming in second. Until his 2015 win, Mazdzer's best finish at the FIL World Luge Championships was sixth in the singles at Whistler, British Columbia, in 2013. His best World Cup season finish was 13th in 2012–13. In December 2014, he won the men's singles event in the luge sprint in the second ever to be held and to be competed in event at the World Cup level in the discipline. Mazdzer was therein victorious at the FIL "Sprint" World Cup event at the Calgary track.