The Sabres announced Thursday that Grigorenko would leave for Russia on Sunday.
"I think it'll be a great opportunity for him to play at the World Junior Championship; it's the best junior kids in the world playing so he'll have that chance and hopefully represent himself very well and it will help further his development," Sabres coach Ted Nolan said after his team's practice on Thursday. "If history teaches us anything, it's that players have to play. I haven't seen too many players develop without playing and he has to play. This will provide a good opportunity."
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, three points and averaged 11:25 of ice time in 18 games for the Sabres this season. He has three goals and eight points in 43 NHL games.