Defending champions Russia beat Denmark 5-2 while Latvia stunned 2013 runners-up Switzerland 2-1 in overtime at the ice hockey world championships on Wednesday.
In Group B played in the eastern Czech city of Ostrava, Russia took a 2-0 lead within 13 minutes with goals by Artemi Panarin and Sergei Mozyakin.
Denmark converted one of their five shots in the second period through Morten Green, but Evgeni Dadonov put Russia two goals ahead once again, just before the second siren.
Thomas Spelling narrowed Russia's lead to a single goal ten minutes before the end.
But the Russians never quite lost control and Mozyakin and St Louis Blues forward Vladimir Tarasenko rounded off the score with two goals within 48 seconds.
Denmark will face the US on Friday.