United States thrashed Denmark to begin their tournament ©IIHF

Hosts United States began their defence of the men's International Ice Hockey Federation (IIHF) World Junior Championships title in style with a 9-0 rout of Denmark in Buffalo.

The Americans, who are hoping to win the under-20 tournament for the fifth time, were rampant in the Group A clash at the KeyBank Center.

Five goals arrived in the first period to put the result beyond doubt.

Casey Mittelstadt and Kieffer Bellows both registered twice with Patrick Harper and Max Jones each helping themselves to a goal and an assist.

Kailer Yamamoto, Andrew Peeke and Dylan Samberg also got on the score-sheet as the US out-shot the Danes 36-17.

"Obviously there's a target on our back," said Bellows. 

"There always is with us being USA Hockey. 

"We're rising up right now.  

"We have to come to every game prepared like it's our last."

Canada also began Group A with a win as they beat Finland 4-2 at the KeyBank Center.

Canada defeated Finland in the other Group A game ©IIHF
Canada defeated Finland in the other Group A game ©IIHF

Boris Katchouk, Sam Steel and Drake Batherson all struck in the first period with Aleksi Heponiemi on target for the Finns as the opening stanza ended 3-1.

Henri Jokiharju reduced the deficit again for the Europeans but Taylor Raddysh restored Canada's two-goal advantage in a match where video reviews were a talking point.

Katchouk's opener was allowed to stand after it was adjudged to have crossed the line before the goal came loose from its moorings, while Finland had another goal ruled out.

Group B also began today with Sweden registering an impressive 6-1 victory against Belarus at Buffalo's HarborCenter.

There was a superb clash between Czech Republic and Russia which the former edged 5-4 at the KeyBank Center.

The top four sides in each group will progress with competition continuing tomorrow.