2009-2010:
Played for the Chicago Young Americans of the MWEHL where he posted 9 goals and 38 points in 35 games. Was selected in the 2nd round, 31st overall by CSKA in the KHL Draft. Was also selected by Val-d'Or of the QMJHL in the 2ns round, 72nd overall, of the CHL Import Draft.
2010-2011:
Posted 5 goals and 27 points in 64 games in his rookie season for Val-d'Or. Appeared for the Detroit Red Wings at the 2011 Traverse City Prospect Tournament.
2011-2012:
Posted 7 goals and 20 points in 46 games for Val-d'Or. Appeared for Russia in 1 game of the 2012 Subway Super Series against the QMJHL All-Stars. Won Silver for Team Russia at the U20 World Junior Championships while paired with Zakhar Arzamastsev on Russia's top pairing. Sergeev posted 1 goal and 2 points in the tournament. Was unranked by NHL Central Scouting and undrafted in the 2012 NHL Entry Draft, making Sergeev an unrestricted free agent. Signed by the Tampa Bay Lightning on July 1, 2012.