The 2004 gold medallists Argentina and Brazil both won their games Sunday in the Olympic football tournament to advance to the quarter-finals, the dpa reported.
Argentina did not play brilliantly in Shanghai, but it controlled the ball and did enough overall to deserve to beat a defensive Australia 1-0.
In the 76th minute, a lacklustre Juan Roman Riquelme played a one-two with Lionel Messi. A pass to the left led Angel Di Maria to cross the ball for Napoli striker Ezequiel Lavezzi to score the winner goal.
The result left Argentina - somewhat slow and predictable in China so far - with six points from two games in Group A, with one more group game ahead, against Serbia on Wednesday.
In Shenyang, Ronaldinho woke up from his lethargy to help Brazil beat New Zealand 5-0.
Anderson opened the score after just three minutes, while Alexander Pato made it 2-0 on the 34th minute. Ronaldinho - who had not scored a goal for many months - added a brace in the 55th and the 61st minute (his second goal came from a penalty shot) while Rafael Sobis set the final 5- 0 in injury time.
In Group C, Brazil has six points from two games, ahead of its final group match Wednesday against host China.
In Group B, Nigeria beat Japan 2-1, while in Group D Cameroon defeated Honduras 1-0.