After a slow start offensively, the U.S. opened things up in the second period en route to a 4-3 defeat of Switzerland on Tuesday, the second day of the World Junior A Challenge, being played at Mariners Center in Yarmouth, N.S.

The U.S. trailed 1-0 after one period, but scored four goals in the second, including three in the first 5:39 of the period, to blow the game open and earn a spot in the tournament semifinals Friday. The U.S. won Group B with a 2-0 record that includes Monday's 9-1 defeat of Canada East.

"We learned tonight that we have to play disciplined hockey," U.S. coach Brett Larson said. "When we played with speed and got the puck in deep we created chances and were rewarded for it. When we committed penalties and turned the puck over we paid the price. To have success in the medal round we need to play consistently for 60 minutes."

After Vince Hinostroza's goal 1:44 into the second tied the game, 2013 NHL Draft prospect Justin Kloos put the U.S. ahead with a goal at 4:41. A strong forecheck allowed J.T. Stenglein to find Kloos in the low slot for the go-ahead score. Just 58 seconds later, Austin Cangelosi finished a three-on-two rush to put Team USA up 3-1. Sheldon Dries closed the big second period with a goal at 13:08.

Switzerland got a pair of goals in the third period to make the game close, but goalie Eamon McAdam helped the Americans win their second straight game, finishing with 22 saves on 25 shots. One of the top draft-eligible goaltenders in the United States Hockey League, McAdam -- who skates for the Waterloo Black Hawks -- has made 48 saves on 52 shots in two games.

In Tuesday's other game, 2013 draft prospect Rhyse Dieno had a goal and three assists to help Canada West to a 7-0 defeat of the Czech Republic. The margin of victory was the largest shutout in tournament history.

Fellow draft candidate Wade Murphy had a pair of goals and goalies Jonah Imoo stopped all 20 shots he faced as the defending champions opened with a victory.

Canada West next faces Russia on Wednesday for first place in Group A and a spot in the semifinals.

Contact Adam Kimelman at [email protected]. Follow him on Twitter: @NHLAdamK