The Sabres announced Thursday that Grigorenko would leave for Russia on Sunday.
The Russian Ice Hockey Federation on Tuesday had released a list of 29 players for a selection camp to be held Dec. 9-20 in Novogorsk, Russia, but Grigorenko's name was not on it.
Grigorenko, chosen No. 12 by the Sabres in 2012 NHL Draft, has played in the previous two WJC tournaments. He helped his country to a silver medal in 2012 after totaling two goals and five points in six games and a bronze in 2013 with two goals and six points in seven games.
The 19-year-old center had two goals and three points in 18 games for the Sabres this season. He has three goals and eight points in 43 NHL games.