In Group A played in Prague, underdog Latvia bested Switzerland to collect its first points at the tournament.
Andris Dzerins scored in the 25th minute and Latvia goalie Edgars Masalskis kept a clean sheet until the 59th minute when Janis Sprukts scored an own goal with Switzerland's Matthias Bieber earning the honours as his team's last
player to touch the puck.
But Kaspars Daugavins scored his third goal at the tournament two minutes into overtime, beating Colorado Avalanche goalie Reto Berra in the Swiss goal to hand Latvia two points.
The result leaves Switzerland in third place in the Group A standings behind Sweden, defeated by first-placed Canada 6-4 after the Swedes were unable to hang on to to a 4-3 lead.
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.