It's hard to argue with perfection. The unbeaten U.S. hammered Switzerland 10-0 on Tuesday to finish first in Group B. The host Swiss, who fell behind 4-0 in the first period, came third with two wins and two losses.

"It was good," said U.S. forward Oliver Moore. "I think our team was consistent throughout all three periods. We controlled the momentum and it was a good game for us. I think it's good to grab momentum going into the quarter-finals."

Quarter-final opponents for each team on Thursday depend on the result of the Czechia-Canada game. The U.S., whose 37-6 goal difference is easily the tournament's best, enters the medal round seeking its first gold since 2017 and all-time record 11th title. The Swiss have only medaled once (2001, silver).

"When we don't have the puck, we want everybody playing defence," said American coach Dan Muse. "When we do have the puck, we want everybody involved in helping to create some offence. So I think we're seeing that right now. "

The top U.S. line dominated versus Switzerland, combining for 13 points. Ryan Leonard shone with a hat trick and two assists. Will Smith chipped in a goal and three assists, while Gabe Perreault had four assists. Smith and Perreault are vying for the tournament scoring lead with 15 points apiece.

Muse praised Leonard: "That's who he is. Ryan Leonard doesn't take days off. I haven't seen it once in two years. So I'm not expecting to see it any time soon. He's always going, every single game, every single practice. He's playing like it's playoff hockey for him all the time."

Cole Eiserman also stepped up again, tallying twice in the first period for the Americans. The 16-year-old phenom leads these U18 Worlds with eight goals. The single-tournament record of 14 goals is shared by Alexander Ovechkin (2002) and Cole Caufield (2019).

The Swiss came out hard in front of the partisan St. Jakob Arena crowd, but couldn’t match the quick-strike offence of Muse’s troops. Shots on goal favoured the U.S. 34-17.

"I'm still proud of the guys and how they competed," said Swiss coach Marcel Jenni. "Of course, the result is for me a little bit too high, but there is no question about who was the better team tonight."

Top Swiss netminder Ewan Huet, who played the first three games (1.33 GAA, 94.5 save percentage), sat this one out to rest up for the quarter-finals.

It took just 15 seconds for the U.S. to draw first blood. Drew Fortescue, a Boston College defenceman, blew a shot past a surprised Christian Kirsch, making his U18 Worlds debut in net for Switzerland.

"I think we weren't ready at the beginning, first shift," said Switzerland's Simon Meier. "They just got a goal. It's not acceptable."

Switzerland got the first power play after Ryan Fine hauled down Simon Meier at the Swiss blue line, and coach Marcel Jenni's team generated good pressure. Yet even though they were narrowly outshooting their North American foes midway through the period, they couldn’t solve U.S. starter Trey Augustine.

Kirsch made a breakaway save on Perreault, but the dam burst soon afterwards. Eiserman scored short-side at 16:11 on the rush, converting a deft James Hagens cross-ice pass.

Just 16 seconds later, Leonard made it 3-0, tipping in Zeev Buium’s rising centre-point wrister. The play was reviewed for a possible high stick and ruled good.

After the Swiss defence failed to clear the puck out of the crease, Eiserman shoveled a backhand through Kirsch's legs for a four-goal lead at 19:07.

The U.S. didn't relent in the second period. At 0:49, Perreault made it 5-0 to culminate a nifty passing play that would have made the Harlem Globetrotters envious. At 11:56, Leonard gave the U.S. a 6-0 lead when he cashed in Perreault's centring pass on the power play.

In the third period, Smith scored at 1:00 with a lightning wrister. Muse gave Augustine a rest, inserting backup goalie Carsen Musser. Musser made 14 saves in the 12-1 win over Norway in his only start.

Leonard completed his hat trick at 6:37 for an 8-0 lead, and Buium coolly scored five-hole on a penalty shot at 7:52 for the ninth goal. Moore rounded out the scoring with 4:28 left.

About facing the Smith line, Simon Meier said: "With their hockey sense and their hands, they're pretty good, and they always try to look for that backdoor pass. So it's really difficult to handle them. But I'm sure if we played them a second time, I think it will be a lot better."

For Switzerland, this marked the 10th loss in 11 U18 Worlds meetings with the Americans. The lone Swiss win was 4-2 on 17 April, 2014 in Lappeenranta, Finland. Denis Malgin scored twice with under four minutes remaining to secure the victory.

Jenni focused on how to approach the 2023 quarter-finals: "Just play our game. I think overall in this tournament, we've played well. We need to stay positive even after this game. Play our game, play fast, and play hard. Then we want to win."