RED DEER, Alberta -- Boston University goalie Drew Commesso made 23 saves and the defending champion United States opened the world junior hockey championship with a 3-2 victory over Slovakia on Sunday night.

Up 3-0 after two periods, the Americans held on after Martin Chromiak scored twice for Slovakia in the final period -- the last with 2:33 remaining.

Minnesota forward Matthew Knies opened the scoring on a two-man advantage with 6:25 left in the first period, and Michigan's Mackie Samoskevich connected 1:43 later with a one-man advantage. Notre Dame's Landon Slaggert scored in the second.

The Americans will continue Group B play Tuesday against Switzerland.

Simon Latkoczy made 39 saves for Slovakia.

"Our guys stuck together and grinded out a tough game,'' U.S. coach Nate Leaman of Providence said. "It's a good first step for our group. We need to keep working hard and improving before we play Switzerland on Tuesday.''

In Edmonton in Group A, No. 1 overall draft pick Owen Power had a hat trick to help Canada beat the Czech Republic 6-3. In the afternoon, Sweden beat Russia 6-3 in Group B in Red Deer, and Finland topped Germany 3-1 in Group A in Edmonton.

Power scored in the first period to put Canada up 3-2, then struck twice in a 1:25 span on a two-man power play midway through the second period to make it 5-3.

"I think pucks kind of just found me," Power said. "Guys did a good job of getting me good pucks in good spots to shoot."

Power was taken by the Buffalo Sabres with the top pick in the July draft. The 6-foot-6 Michigan star is the first Canadian defenseman to score three goals in a game in the event.

"There's been a ton of really good players come and play in these tournaments, so I had no idea that no one had got a hat trick, so definitely just surprised." Power said. "Doing it at this stage and wearing a Canadian jersey is definitely pretty special."

Mason McTavish, Donovan Sebrango and Olen Zellweger also scored for Canada, and Cole Perfetti had three assists. Dylan Garand made 14 saves. He signed an entry-level deal with the New York Rangers last week.

Michal Gut, Pavel Novak and Stanislav Svozil scored consecutive goals to give the Czech Republic a brief 3-1 lead in the first period. Jakub Malex stopped 30 shots.

Sweden's Theodor Niederbach scored midway through the third period to thwart Russia's comeback bid.

After Russia's Matvei Michkov scored twice in a 41-second span early in the third to cut the lead to 4-3, Niederbach beat goalie Jaroslav Askarov to restore a two-goal margin.

Oskar Olausson, Emil Andrae, Alexander Holtz, Simon Edvinson and Daniel Ljungman also scored for Sweden, and Jesper Wallstedt made 27 saves. Fyodor Svecjkov also scored for Russia, and Askarov stopped 13 shots.

Samuel Helenius scored twice in Finland's victory over Germany. Joel Maatta also scored, and Leevi Merilainen made 23 saves. Luca Munzenberger scored for Germany, and Nikita Quapp stopped 19 shots.

The IIHF Council said Sunday that the same 10 teams in the top division will return for the 2023 event in Novosibirsk and Omsk, Russia. Belarus was promoted from Division IA this month, bringing the field to 11.