Auston Matthews scored a hat trick for the U.S. and Alex Nedeljkovic made 28 saves en route to a shutout, his first in the tournament.
"The guys played really well tonight. It was a little bit of a question how we were going to come out, but we established our forecheck early on, and we got pucks on the net. Couldn't ask for a better game," Nedeljkovic said.
"Everybody on the ice helped me today, my linemates played unbelievably today," Matthews said of his hat-trick.
Team USA had lost only one game in the preliminary round, the one against Sweden, but even in that one they only let in one goal. All in all, they were only scored against five times in the preliminary round’s four games – tied for lead in Group A, with Sweden – while the Czechs’ goal difference was 12-10 in their four games in Group B.
Team USA's goal difference after five games, including the quarter-final, is an impressive 25-5.
"It's not just me, or just the defence, it's the forwards, too. Everybody has bought into the system, and that's where we get our offense from: we play well in our own end, and create chances building on that," Nedeljkovic explained.
The Czechs knew they would need to keep the Americans off the scoreboard to win as the U.S. defence probably wouldn’t give more than a couple of goals at best.
Unfortunately for the Czechs, the Americans scored first. They forechecked hard and about five minutes into the game, they clawed the puck to themselves in the Czech corner, Brock Boeser carried it around the net and dropped it to Nick Schmaltz who lifted it to the back of the net with a quick backhander to give Team USA the lead at 5:17.
"The quarter-final is the most important game of the tournament and we didn't play well. They were really strong around the net and we didn't protect our house. They scored their goal around our net," said Czech forward David Pastrnak.
With 4:46 remaining, the Americans extended their lead to two goals when two Czech defencemen couldn’t clear the rebound that Vitek Vanacek left when he made the save on Brandon Carlo’s shot from the point. Instead, Christian Dvorak stepped in and backhanded the puck to the back of the net.
The Czech coach Jakub Petr made a goalie change during the first intermission, and Ales Stezka, wearing a classic number 2, took his place between the pipes.
Just 4:15 later, he had succumbed to the Americans for the first tie. The Czechs were breaking out from their end, but Will Borgen intercepted a pass on the Czech blueline, Auston Matthews took a few strides in and fired a wrist shot that beat Stezka on his glove side to give Team USA a 3-0 lead in the game.
Matthews scored his second just 4:53 later on a power play. Zach Werenski and Schmaltz played the puck to Matthews who had half the net to shoot for, and he didn’t miss it. Team USA had a 4-0 before the game was halfway through.
With 1:53 remaining in the period, the U.S. made it 5-0 while shorthanded. Scott Eansor simply snatched the puck from a Czech defenceman on the U.S. blueline, and got on a breakaway. He deked Stezka and shot the puck through his five-hole.
Matthews completed his hat-trick 24 seconds into the third period when he simply danced inside the Czech box and fired a wrister to the back of the net. That was his seventh goal in the tournament, most of all players.
"It's awesome to play with him. We played together last year and this year, coming into the tournament they put us together," said Matthew Tkachuk.
But the Americans weren't done yet and 11:53 into the third period, Ryan McInnis and Ryan Donato played the puck into the Czech zone and with two drop passes created a chance to Alex DeBrincat, who fired a wrist shot from the slot to make it 7-0.
"We haven't watched too much of Russia's game. I know they had a close game against Denmark today, but you can't look at that. We know it's a big and skilled team," Tkachuk said.