The 2015 Asian Cup knockout stages began in good fashion with tournament favourites South Korea and Australia winning hard-fought quarter-final matches by identical 2-0 margins against Uzbekistan and China in Melbourne and Brisbane respectively.

South Korea defeated Uzbekistan in the day's earlier kick-off at the Melbourne Rectangular Stadium, with Son Heung-min netting both goals in extra time.

The Uzbeks matched South Korea in normal time but were left to rue two defensive lapses that resulted in Bayer Leverkusen star Son scoring in the 104th and 119th minutes of extra time.

Son's first goal was the result of an error by full-back Shukhrat Mukhammadiev, who tried to dribble his way out of defence only to be caught out by Kim Jin-su, who sent in a cross for Son to head past impressive Uzbek goalkeeper Ignatiy Nesterov.

As Uzbekistan began pushing more men in search of the equaliser, Son found space in front of goal and sent a rasping shot beyond the fingertips of Nesterov to put the game to bed.

In the semifinal on Jan. 26 in Sydney, South Korea will face the winner of Friday's quarter-final between Iran and Iraq.

In the day's second quarterfinal, played in Brisbane in front of a full house, it was the turn of another global star to score a brace as Australia rode on iconic midfielder Tim Cahill's two strikes to defeat Alain Perrin's China, who failed to threaten Australia keeper Mathew Ryan's goal for most part of the game.