Rask joins a number of players who have opted to play in the Czech Republic, including teammate Andrew Ference. Edmonton's Ales Hemsky, Dallas' Jaromir Jagr and fellow goalies Ondrej Pavelec and Michal Neuvirth will also play there.
Rask wasn't the only Bruin discovered Monday to be heading out of the country to play during the lockout. Bruins defenseman Dennis Seidenberg confirmed to ESPNBoston.com that he will join his younger brother Yanick in playing for Addler Mannheim of the German League. And forward Rich Peverley will head to Finland to play for JYPin.
Rask, Seidenberg and Peverley join Ference, forward Tyler Seguin (Switzerland) and goalie Anton Khudobin (Russia) as Bruins confirmed to play overseas this winter. Forward David Krejci is also reportedly close to a deal to play in Russia.
Bruins center Patrice Bergeron told ESPNBoston.com on Monday that he is still exploring his options and hasn't decided yet whether to play elsewhere. He added he was continuing his normal workout schedule for this time of year.
Defenseman Shawn Thornton said he plans to join a foreign team during the lockout but is still undecided on which one.
With goalie Tim Thomas' decision to take a year off from hockey, Rask was slated to be the full-time starter in Boston for the first time in his career. The 25-year-old native of Finland played in 23 games last season, finishing the year with a 11-8-3 record, .929 save percentage and 2.05 goals-against average. In June, he signed a one-year contract with the Bruins worth $3.5 million and is scheduled to become a restricted free agent after this season.
ESPN.com's Craig Custance and ESPNBoston.com's Joe McDonald and James Murphy contributed to this report.