Seventeen goals were scored in four games on Monday in Canada, with Japan beginning their Women's World Cup defence in victorious fashion.
Reigning champions Japan and perennial contenders United States both started their Women's World Cup campaigns with a win, as Cameroon smashed six goals past Ecuador.
On a high-scoring day in Canada, two of the four matches on Monday saw six goals scored, while Megan Rapinoe notched a brace in USA's 3-1 victory over the Matildas.
But Japan, who defeated USA on penalties to lift the 2011 World Cup, needed just one goal to overcome Switzerland.
A contentious penalty saw the title-holders overcome the Swiss 1-0, with goalkeeper Gaelle Thalmann judged to have fouled Kozue Ando in the process of saving the Japanese striker's shot.
Aya Miyama converted the spot-kick in the 29th minute.
Spectators in Winnipeg were treated to 10 goals in a double-header featuring the four teams in Group D with Sweden and Nigeria playing out a pulsating 3-3 draw before the Matildas 3-1 loss to the USA.
In the earlier match, Sweden led 2-0 just after the half-hour mark but the youthful Nigerians dragged themselves level just after the break with Ngozi Okobi and Asisat Oshoala scoring within four minutes of each other.
Linda Sembrant put Sweden ahead in the 60th minute but Nigeria deservedly claimed a point after Okobi picked out Francisca Ordega's run and the latter slotted her shot between the legs of goalkeeper Hedvig Lindahl.
There were also six goals scored in the opening match in Vancouver, with Cameroon arriving at the World Cup in style.
Cameroon scored three goals in each half against fellow World Cup debutants Ecuador with Gaelle Enganamouit registering a hat-trick, while the South Americans had to play the final 24 minutes with 10 players after Ligia Moreira was sent off.
Three of Cameroon's goals came from the penalty spot.