But Mathewson, who led all players with three goals, led the late rally. She responded with two quick strikes from the perimeter. The second one, with 1:33 left in regulation, tied the score and forced the shootout.
The United States didn't miss in the shootout, as Maggie Steffens, Mathewson, Kelly Rulon and Lauren Silver all scored.
Armstrong, the veteran goalie, got her hands on Canada's first attempt, then clinched the win when she just deflected Krystina Alogbo's shot off the bar.
"It's nice playing with someone who obviously has a ton of experience," Anae said of Armstrong, who made eight saves. "She's one of the best goalies in the world, if not the best. There's only everything to learn. It's nice to ask her questions basically about anything, about traveling to different players on certain teams, certain tendencies. It's really nice to play with Betsey. And she's cool, so that's always a benefit."