EDMONTON, Alberta -- Malaika Underwood led an offensive explosion and Stacy Piagno tossed a gem to help lead the USA Baseball Women's National Team to a 17-4 win over Canada in the semifinals.

The victory advances Team USA (6-2) to the gold medal game against Japan Sunday night at 7 p.m. (ET). The U.S. also assures itself of a medal for the fifth consecutive World Cup.

Piagno was masterful for 5 2/3 innings as she faced the minimum through five innings. Canada tallied two hits in the first four innings, but each runner was erased on a double play. Four runs crossed the plate for Canada in the sixth, but only one was earned. Marti Sementelli tallied the final out for the U.S.

Team USA opened up an early 1-0 lead in the second and never looked back. Underwood singled to lead off the inning, stole second and moved to third on a base hit by Michelle Snyder. Bessie Noll gave the U.S. the lead with a sacrifice fly.

A seven-run third inning put the U.S. firmly in control. Jill Barrett worked a lead-off walk and was standing on third after a Natalie Land base hit. A fielder's choice off the bat of Caitlin Everett made it 2-0. Underwood doubled and an error pushed the lead to four and loaded the bases. Alexa Maldonado launched a fly ball to deep right field for a bases-clearing triple. An errant throw back to the infield allowed Maldonado to score for an 8-0 lead.

Underwood started a two-out rally in the fourth inning with a triple down the right field line. Snyder drove her in with a base hit to right.

Twelve batters came to the plate in the top of the sixth and eight scored as the U.S. opened up a 17-0 lead. A lead-off walk to Holmes started the string of hitters. Underwood drove her in with her second double of the game. Snyder followed with an RBI double and moved to third on a throwing error. Noll's second sacrifice fly of the game pushed the lead to 12-0.

With two on and two out, the U.S. pushed across five more runs. Land singled home a run and a two-base error by the Canadian pitcher allowed two runners to score for a 15-0 lead. Holmes dumped a single into centerfield and Underwood collected her second double of the inning to cap the scoring.

Needing eight runs to keep the game going, Canada tried to mount a rally in the bottom of the sixth. With two on and nobody out, an error allowed Canada's first run of the game to cross the plate. A sacrifice fly, a base hit and a bases loaded walk made it a 17-4 contest before Sementelli struck out Bradi Wall to end the game.