Canada maintained their perfect record at the IIHF Ice Hockey World Championship with ease on Monday, but Finland were made to work much harder in order to claim their third successive preliminary-round win.

Defending champions Canada thrashed Belarus 8-0, Ryan O'Reilly scoring twice, to take their aggregate score from three matches to 20-2.

Captain Corey Perry hailed the efforts of his young team, stating: "There's a lot of offense, there's a lot of skill, there's a lot of youth. We're excited to be here, put this jersey on, and play for our country."

Finland have also yet to drop points in Group B, yet they faced a stern test against the United States before running out 3-2 winners.

Leo Komarov's power-play strike in the third period, 20 seconds after the USA's Patrick Maroon had been sin-binned for tripping, ultimately proved decisive.

Russia goaltender Sergei Bobrovsky impressed with 27 saves as the hosts beat Latvia 4-0.

Bobrovsky held firm throughout almost 12 minutes of power-play time for Latvia and still did not concede when Russia were two men short for 75 seconds towards the end of the second period.

"That was a critical moment," said Bobrovsky. "It was only 2-0 at that point, and if they had scored, it might have been a different game."

In Monday's other match, Czech Republic came from two goals down to beat Sweden 4-2 and open up a two-point lead over Russia at the top of Group A.