Team GB are on course to top Group E as they hold a 1-0 half-time lead over Brazil.
Great Britain took the lead after just two minutes when Stephanie Houghton evaded the challenge of Andreia before slipping the ball past the goalkeeper.
Brazil so nearly levelled moments later when Cristiane advanced on goal, but she fired her effort wide from outside the box before seeing a shot saved by Karen Bardsley.
Marta was next to come close for Brazil after 14 minutes, while Jill Scott might have met a Kelly Smith pass moments later, but it drifted out of play.
Marta and Cristiane continued to influence the match as the half progressed, with the pair both coming close with 25 minutes on the clock. Team GB remained a threat, however, and Smith just fired an effort past the post after 30 minutes.
Team GB continued to create chances, and it might have fallen for Scott inside the box, but Erika just managed to block the danger.
Both sides had chances on the break in the latter stages of the half, but Houghton's early strike remained the difference.
