kovalenko learned to played as youth within the ranks of the lokomotiv yaroslavl hockey school, while his father played with the khl club. unable to play in the renowned style of his father, who was known as "the tank", nikolai focused on a more technical skill based game. he made his debut in the mhl with loko yaroslavl during the 2015–16 season, scoring 4 goals and 5 points in 4 games as a 16-year old. showing offensive potential, through loko's second tier junior club, loko juniors, kovalenko was promoted to remain for the majority of the 2016–17 season in the mhl, producing a modest 14 points in 35 games.