Appearing in men’s football at the Games for the first time since Beijing 2008, the Olyroos are considered outsiders in a daunting group featuring Argentina, Spain and Egypt.

Christine Sinclair opened the scoring in the sixth minute to give Canada the lead but Japan dug deep despite a missed penalty to force the draw with Mana Iwabuchi finding the back of the net in the 84th minute.

A fast start by Brazil saw Marta and Debinha give the two-time Olympic silver medallists a 2-0 lead before China PR asserted themselves in the tie under the hot afternoon sun.

Brazil, however, added goals through Marta, Andressa Alves and Beatriz late in the second half for the emphatic win over Jia Xiuquan’s Steel Roses .

Winless in five matches under new boss Tony Gustavsson coming into the clash, the Matildas were too strong for their neighbours with first half goals from Tameka Yallop and Sam Kerr providing enough of a buffer to withstand a late New Zealand push which included a last-gasp goal from Gabi Rennie.

Following Sweden’s surprise 3-0 win over the United States earlier on Wednesday, the result puts Australia in second place in Group G ahead of their clash with the Swedes on Saturday.

Coach Kim Hak-bum's side will want to kick off their Group B campaign with a winning start but they will need to improve upon defensive issues that arose in their two warm-up matches against Argentina and France last week.

In both games, errors at the back presented their opponents with opportunities that they did not spurn and the absence of gifted centre-back Kim Min-jae, who was originally selected as one of the three overage players but was not released by club Beijing FC, seems to have hamstrung the defence.

The Japanese have their sights sets on winning a first medal since 1968, when striker Kunishige Kamamoto led the country to the bronze medal in Mexico City with a 2-0 win over the competition’s hosts.

Moriyasu’s side have impressed during the build-up to the competition and go into the meeting with the South Africans unbeaten in their last five games, during which time they have claimed some impressive results.

The fixture marks the start of a challenging group for the young Green Falcons who were also pitted against both finalists from Rio 2016 - Brazil and Germany.