Abby Wambach scored for a fourth straight match, second-half substitute Sydney Leroux added a late insurance tally and goalkeeper Hope Solo extended her streak without allowing a goal to 346 minutes to give the two-time defending champion Americans a 2-0 victory over New Zealand in Newcastle, England.
In Coventry, England, Christine Sinclair scored her third of the 2012 Games and Jonelle Filigno had her first as Canada beat host Britain 2-0 and advanced to the semifinals for the first time at a world championship since reaching the semifinals at the 2003 Women's World Cup.
Monday's meeting in Manchester's Old Trafford will be the third this year and 52nd in history between the North American neighbors, with the United States having won 43 and drawn five others. The match will feature the second- and third-most prolific scorers in women's soccer, Wambach (142 goals) and Sinclair (140).
In Newcastle, the United States controlled most of the play, outshooting New Zealand - playing in a knockout stage of a world championship finals for the first time - 15-7 and earning six corner kicks to the "Football Ferns'" zero.
Morgan put chances wide in the 10th and 17th minutes before turning provider in the 27th. Settling the ball on the left side of the penalty area, she worked free of defender Abby Erceg and sent a low cross to the back post where Wambach touched it in with a sliding lunge of her right foot.
The Americans continued to dominate through the second half as New Zealand was limited to chances from distance by Ria Percival and Katie Hoyle.
Goalkeeper Jenny Bindon raced off her line several times to diffuse U.S. opportunities, including one in the 73rd when her head and Morgan's knee collided leaving both momentarily injured.
Leroux replaced Morgan in the 80th minute and scored her first goal in the Olympics seven minutes later. She ran onto a ball down the left from Tobin Heath our ot midfield, held off a challenge from New Zealand captain Rebecca Smith and drove a ground-skimming shot into the far-side netting.
In Coventry, Filigno gave Canada the lead in the 12th minute off Sofie Schmidt's out-swinging corner to the top of the box. Filigno volleyed it with her right foot off the bounce and it sailed into the upper near corner over the head of defender Jill Scott standing on the line.
The goal silenced the boisterous home crowd at Rich Arena, which appeared to be at or near capacity. It was the first goal allowed by Britain in the Games after first-round victories over New Zealand, Cameroon and Brazil.
Sinclair doubled the lead 14 minutes later, curling a right-footed 25-meter free kick around the wall and bouncing it on the line before it dropped inside the right post.
Britain had its chances, particularly when Scott raced in to the middle of the area to get to Karen Carney's well-driven cross from the right. But the opportunity was wasted when she headed well high in the 23rd minute.
British forward Eniola Aluko howled, along with the partisan British crowd, for a penalty after she was brought down on the left side of the area by Rhian Wilkinson, but her protest was ignored by Japanese referee Sachico Yamagishi.
Canada's is making only its second appearance in the Olympics, having been beaten in extra time by the United States in the quarterfinals in 2008. It hasn't beaten the Americans in 26 matches since 2001.
The United States has three gold medals and a silver in the four Olympics since women's soccer was introduced to the Games in 1996.