In 2012, Koptelov competed at the 2012 FINA World Swimming Championships (25 m) in Istanbul, Turkey making it to the semi-finals in men's 50 m butterfly. At the 2013 Summer Universiade in Kazan, Kopelov was member of the Russian Team that won gold in men's 4 × 100 m medley (with Vladimir Morozov, Kiril Strelnikov and Andrey Grechin) and a bronze medal in 100 m butterfly. In 2014, Koptelov finished 8th in 200 m butterfly at the 2014 European Championships.