Two-time Olympic men's soccer champion Argentina was stunned 2-0 by Australia in their opening game at the Tokyo Games on Thursday.

In its first Olympic game since 2008, Australia took the lead through Lachlan Wales' tap-in the 14th minute at the Sapporo Dome.

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Argentina had Francisco Ortega sent off after being booked twice late in the first half. Marco Tilio then secured the victory in the 80th, just a minute after coming off the bench.

Australia is top of Group C ahead Egypt and Spain, who drew 0-0 in the other game.

The Argentines won Olympic gold in 2004 and 2008. Australia's best showing was fourth place in 1992.