Canada got their Women's World Cup campaign up and running with a 1-0 win over Cameroon thanks to Kadeisha Buchanan's first international goal, while Japan were held by Argentina on Monday.
Kenneth Heiner-Moller's side controlled much of proceedings in Montpellier, though did not craft an opening until Buchanan headed in on the stroke of half-time.
Having hit the woodwork prior to Buchanan's effort, Nichelle Prince squandered a golden chance to further Canada's lead just before the hour, and would have been made to pay had Claudine Meffometou directed her effort on target.
Ultimately Prince's miss mattered little, though, as Canada moved top of Group E, which also includes New Zealand and Netherlands.
In Monday's earlier fixture, 2011 World Cup winners Japan were held to a frustrating 0-0 draw by Argentina in Group D.
Asako Takakura's side have reached the final in the last two editions of the tournament, but were wasteful in Paris against a side that had lost all six of their previous World Cup games, conceding 33 goals in total.
Yui Hasegawa passed up the best opportunity, slicing a weak left-footed strike well wide midway through the second half as Japan failed to move level with group leaders England.