Sweden, Russia, Slovakia and hosts Canada secured berths in the last four of the International Ice Hockey Federation World Championships after each battling to quarter-final victories.
Playing in front of a raucous and partisan crowd of 18,448 at the Air Canada Centre in Toronto, Canada were by far the most emphatic of the four winners, sweeping aside Denmark 8-0.
Connor McDavid was the outstanding star for the host nation, with a superb goal in the second period, along with two assists, while linemate Curtis Lazar also found the net twice.
"It's a dream come true to skate out there," McDavid said.
"The atmosphere was pretty special, but that's kind of what I was expecting, the fans were great."
The Canadians, who are yet to win the annual global event for under-20 athletes since a run of five successive victories was halted in 2010, will now face Slovakia in the last four, whose only previous medal was a bronze back in 1999.
Slovakia beat Central European rivals Czech Republic 3-0 to make the semi-finals for the first time in six years, with Peter Cehlarik, Martin Reway and Michal Kabac scoring the goals.
But, while Canada were the most comfortable winners, it was Russia who won the closest and most entertaining clash, after scraping home 3-2 against fierce rivals United States.
The two superpowers have long endured perhaps the bitterest rivalry in senior ice hockey, with a 3-2 overtime victory for the US in last year's Sochi 2014 Olympic tournament one recent highlight, but it was the Russians who finished on top this time around.
Ivan Barbashyov, Alexander Sharov, and Sergei Tolchinski all scored in an immensely physical battle, in what marked the second successive year Russia had knocked out the US at the quarter-final stage.
"Before the game everyone said we are underdogs," said coach Valeri Bragin.
"I agree with that because the American team has a lot of skilled players and is well organised, but we capitalised on our chances in the beginning of the game, and we had solid goal-tending.
"Our team showed real team spirit."
They will next face Sweden, who overcame defending winners Finland 6-3 in a repeat of last year's final, albeit with a different outcome.
It marked the ninth successive occasion the Scandinavian nation have made the last four, and they will now be confident of gaining a third World Junior Championships title, following triumphs in 1981 and 2012.
Both semi-finals will take place on Sunday (January 4) ahead of a final and bronze medal match on Monday (January 5).
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