At the 2008 World Junior Championship Filatov made his debut with Russia's under-20 junior squad. At the tournament, he scored four goals and added five assists, leading the Russian squad in total points and placing second to Viktor Tikhonov in goals scored. The Russian team captured bronze at the tournament after defeating the United States 4–2. Filatov scored two goals in the bronze medal game, and was named Russia's best player of the game by the IIHF.