Canada beat Switzerland 3-2 in overtime Thursday night. Severson tied it with 0.4 seconds left on a goal confirmed by video review. Stone ended it at 5:07 of the 3-on-3 overtime.
In the semifinals Saturday, Canada will face the Czech Republic, and Russia will play Finland.
In Bratislava, Nikita Gusev and Mikhail Sergachyov each had a goal and two assists in Russia's 4-3 victory over the United States. Kirill Kaprizov and Mikhail Grigorenko also scored. Brady Skjei, Noah Hanifin and Alex DeBrincat scored for the Americans.
Finland beat Sweden 5-4 in overtime in Kosice. Marko Anttila tied it for Finland with 1:29 left and Sakari Manninen won it in overtime.
The Czech Republic topped Germany 5-1 in Bratislava. Jan Kovar scored twice for the Czechs.