Czechia was missing a key player for its opening game of the World Junior Hockey Championship against Canada.
Star defenceman Radim Mrtka was not in the team's lineup for what ended up as a 7-5 loss. Mrtka was not initially registered on the official roster because of a health concern, the team said Friday.
Czechia coach Patrik Augusta said that Mrtka will play at some point during the tournament.
The 18-year-old was picked ninth overall by the Buffalo Sabres in this year's NHL Draft.
Mrtka has one goal and 15 assists in 14 games for the Seattle Thunderbirds this season, his second year with the WHL squad.
The six-foot-six Mrtka started the season with the AHL's Rochester Americans, registering one assist in four games.