Michael Spacek registered the decisive goal with just one minute, 18 seconds left on the clock at the Centre Bell sports complex in Montreal.

The 19-year-old cut to the middle of the ice and lofted a long shot past Finland goalkeeper Veini Vehvilainen to settle the Group A clash.

Team-mate Daniel Krenzelok had given Czech Republic an early lead that was promptly cancelled out by Joona Luoto.

"It was a good feeling," Spacek, who is playing in his third straight IIHF World Junior Championship, said of his winning goal.

"This goal is special in my career."

Despite suffering defeat, Finland captain Olli Juolevi remains confident his team can defend their crown.

"We can still win this tournament," he said.

"We haven’t lost anything, kind of.

"It’s just one game."

Today’s other match in Group A saw Sweden thrash Denmark 6-1.

Alexander Nylander led the way with a brace for the 2012 gold medallists, while Carl Grundstrom, Rasmus Dahlin and Joel Eriksson Ek chipped in a goal and an assist apiece, and Jonathan Dahlen added a single.

Nikolaj Krag scored a late consolation for Denmark, who will look to bounce back tomorrow when they face Finland.

Tomorrow’s other Group A encounter pits Czech Republic against Switzerland.

Hosts Canada got their Group B campaign off to a good start today, beating 2016 runners-up Russia 5-3 at the Air Canada Centre in Toronto.

Tyson Jost’s early opener for the home nation was cancelled out by Mikhail Sergachyov to make it 1-1 going into the second period.

The home nation pushed on thereafter though and had established a 4-1 lead by the 44th minute thanks to goals from captain Dylan Strome, Nicolas Roy and Mathew Barzal.

Russia’s Kirill Kaprizov reduced the deficit with just under 15 minutes remaining, only for Strome to notch his second and Canada’s fifth goal of the game.

Yegor Rykov completed the scoring but it was nothing more than a consolation for Russia.

Joining Canada at the top of Group B is the United States, who eased to a 6-1 win over Latvia.

The Latvians looked as though they were going to put up a good fight when Renars Krastenbergs brought them back onto level terms following Patrick Harper’s deadlock breaker.

However, their opponents had other ideas and went onto claim a comfortable victory courtesy of a brace from Clayton Keller and one goal apiece for Colin White, Jeremy Bracco and Jordan Greenway.

The Group B schedule for tomorrow is made up of Latvia’s meeting with Russia and Canada’s encounter with Slovakia.