2010-11: Dmitrii Sergeev played for Traktor Chelyabinsk’s 1996-team which was the top team in Ural Region and played for the Russian U16 championship. He also was chosen to represent the Ural region in U15 play. Sergeev scored 14 goals with 19 assists and had 58 penalty minutes in 41 regular season games and scored 4 goals with 5 assists and 4 penalty minutes in six games at the Ural tournament in Magnitogorsk. Sergeev scored 3 goals with 4 assists and was -1 with 2 penalty minutes in six games at the U16 Russian Championships. Traktor finished fourth; falling in overtime to Neva St. Petersburg in the bronze medal game. In five games with the Ural Region U15 team Sergeev had 3 assists and was +7 with 4 penalty minutes.
2011-12: Sergeev skated for Avangard Omsk in the Russian U17 championship after playing for Traktor Chelyabinsk during the Ural Region season and played for Russia’s U16 team in international play. In five games for Avangard in St. Petersburg he scored 2 goals with 1 assist and was +4 with 4 penalty minutes. Omsk won a silver medal after falling to Ak Bars Kazan in the championship game. In 34 games for the Traktor 1996’s he scored 12 goals with 14 assists and 14 penalty minutes. Sergeev scored 1 goal with 3 assists and was +7 with 6 penalty minutes in six games for Russia’s U16 team at the European Youth Winter Olympic Games and was +8 with 2 assists and 35 penalty minutes in six other games for the team.
2012-13: Sergeev played for Traktor Chelyabinsk’s U17 team and represented Russia in three international tournaments including the 2013 U17 World Hockey Challenge in Canada. He scored 4 goals with 12 assists in 28 games in Ural Region play as Traktor advanced to the Russian championship; falling to Avangard Omsk in overtime in the third place game. Sergeev was -4 with no points and 2 penalty minutes in six games at the Russian championship. He had 1 assist and 24 penalty minutes in six games for Russia at the U17 WJC and in five other international games scored 1 goal with 1 assist and was +2 with 4 penalty minutes. Sergeev was selected by Traktor in the first round (31st overall) of the 2013 KHL Draft and was chosen by Kitchener in the first round (23rd overall) of the CHL Import Draft.
2013-14: Sergeev joined the OHL’s Kitchener Rangers in his first season in North America and skated in 49 games; missing nearly a month early in the season with a hip injury. He scored 2 goals with 7 assists and was +5 with 22 penalty minutes. Kitchener finished last in the Midwest Division with the OHL’s second-worst record and missed the playoffs. Sergeev was not among the 210 North American skaters in Central Scouting’s final rankings — though he did appear in the International Scouting Service’s Top 100 prospects — but was not selected in the 2014 NHL Draft.
2014-15: Sergeev attended training camp with the St. Louis Blues as an undrafted free agent, signing a three-year entry-level contract in September 2014 before returning to Kitchener for his second OHL season. He skated in 54 regular season games and scored 5 goals with 23 assists, finishing +8 with 44 penalty minutes. The Rangers finished fifth in the Midwest Division, falling to London in a first-round series. Sergeev had 2 assists and was -7 with 8 penalty minutes in six playoff games.
2015-16: Sergeev returned to Kitchener for his third season with the Rangers. He played for Russia in the 2015 Subway Series against the OHL all-stars and at the 2016 World Junior Championship. Struggling to stay healthy once again he played 49 regular season games. Sergeev was +5 with 2 goals, 7 assists and 22 penalty minutes. Kitchener, after a fast start, finished third in the Midwest Division and reached the second round in the playoffs. Sergeev had 2 assists and was -1 with 5 penalty minutes in four playoff games. He was -2 with no points nor penalty minutes in one game during the Subway Series and was -3 with no points and 2 penalty minutes in seven games at the World Juniors in Helsinki. Russia won a silver medal, falling 4-3 in overtime to host Finland in the championship game.
Sergeev is a big defenseman with some offensive ability and a strong physical presence to his game. His positional play, particularly in his own end and in open areas, is still maturing. His development has been hampered due to injury and he has not yet dominated on the consistent basis of which his ability level suggests he is capable.
Sergeev played for the Kitchener Rangers in 2015-16 and was part of Russia's silver medal-winning U20 team at the World Junior Championship in Finland. He will attend training camp with St. Louis looking to earn a spot with the AHL's Chicago Wolves but after missing significant time over the past two seasons could return to the OHL for an overage season. Sergeev has a combination of size and offensive tools that suggest he can be an effective puck mover from the blueline. A lack of mobility and positional awareness at times, possibly due in part to the time he has missed to injury, hampered his development during his junior career.