The Matildas have blown a two-goal lead against Germany at the Corinthians Arena, meaning they will need a convincing win in their third and final group game against Zimbabwe to progress to the knockout stage.

Against the run of play, Australia hit the front courtesy of first half goals from Sam Kerr and Caitlyn Foord.

But the Germans struck just before the break and Saskia Bartusiak prodded home two minutes from time to secure the 2-2 draw.

The result leaves Canada on top of Group F on six points, while the Germans are on four points.

After losing to Canada on the opening day the Australians, now on one point, are third in their group ahead of Zimbabwe, which lost its first two games.

The women's competition comprises of three groups of four teams, with the top two sides automatically progressing to the knockout stage. The best two third-placed sides also progress.

Boomers, Opals off to solid start

Liz Cambage (right) starred for the Opals against Brazil. ( AP: Carlos Osorio )

The Boomers led at every change to run out comfortable victors against France, winning their opening match 87-66.

Patty Mills (21 points) was Australia's leading scorer, while Andrew Bogut (18 points) made a successful return from a knee injury that threatened to rule him out of the Games.

In the women's competition, the Opals ran over the top of host nation Brazil in the final quarter to win 84-66.

After Brazil led at half time, Australia held a slender four-point lead at the end of the third quarter.

Liz Cambage was Australia's top scorer with 20 points, and also grabbed 14 rebounds.

The Opals play Turkey on Monday (AEST) while the Boomers return to action against Serbia on Tuesday (AEST).

Women's sevens demolish rivals

Australia's women's sevens side began their Rio campaign in stunning fashion, thrashing Colombia and Fiji at the Deodoro Stadium.

Tipped as one of the tournament favourites, the Pearls racked up a combined 89 points while both opponents were scoreless.

In the opening match against Colombia, Sharni Williams began the onslaught after 56 seconds. The Australians crossed five times in the opening period and scored four tries in the second.

Fiji wasn't able to restrain Australia either — it was hammered 36-0.

Australia faces the US on Monday (AEST).

Charlotte Caslick was a central figure in Australia's try-fest against Colombia and Fiji. ( Getty Images: David Rogers )

Mixed results for Kookaburras and Hockeyroos

Australia's men's hockey team defeated arch rival New Zealand 2-1 in their opening pool game at the Olympic Hockey Centre.

Chris Ciriello and Matt Gohdes put the Kookaburras 2-0 up inside the opening 25 minutes, before New Zealand clawed a goal back on the half-hour mark.

The Hockeyroos were beaten 2-1 by Great Britain in their match at the same venue.

Lily Owsley put Team GB in front before Georgina Morgan equalised for Australia in the 33rd minute.

But Alex Danson restored the lead in the 43rd minute, twisting past the Australian defence before smashing a reverse-stick shot past goalkeeper Rachael Lynch.

Brazil hangs on in water polo thriller

Brazil's bench celebrates after a goal. ( Reuters: Laszlo Balogh )

Australia's men's water polo team suffered a narrow loss to Brazil, going down 8-7 at the Maria Lenk Aquatic Centre.

Brazil led for most of the contest, but the Australians were never far behind.

Adrian Baches's goal for the home side in the sixth minute of the final quarter effectively ended the contest, pushing Brazil's lead out to two goals.

John Cotterill scored with 42 seconds to play, giving the Aussies slight hope, but the host nation held on.