BRISBANE - Tim Cahill's brilliant double strike sank China and took Australia into the Asian Cup semi-finals on Thursday as Son Heung-Min defied illness to lead South Korea into the last four.

Hosts Australia had the upper hand against China without crafting the breakthrough, until 35-year-old Cahill pulled out a stunning bicycle-kick just after half-time. The latest uber-strike from Cahill, whose World Cup volley against the Netherlands was short-listed for goal of the year, was followed by a trademark header for the 2-0 win. Australia's victory ended an encouraging tournament from China, who won all three group games for the first time to end their 11-year absence from the knock-out stages.

The Socceroos will now face either Japan or UAE at Newcastle's modest Hunter Stadium, the smallest of the Asian Cup venues, on January 27. "This is a big win for us, it's something that I knew deep down was going to happen before the game, because I believe in this team," said Cahill. "I had to wait for my chance and I took two of them tonight out of three and I'm pretty happy." The Socceroos deserved the win against a willing but outgunned Chinese side, who scrambled well in the first half but folded under the weight of possession enjoyed by the Australians. After Cahill's goals, China refused to concede and they forced two diving saves from Australian keeper Mathew Ryan, but ultimately paid for their lack of fire-power.

Earlier in Melbourne, Bayer Leverkusen's Son fought off the lingering effects of a flu bug to strike twice in extra time and see off Uzbekistan -- before being stretchered off due to sheer exhaustion. The man dubbed "Sonaldo" by his team-mates scored with a diving header after 104 minutes and slammed home a second moments before the final whistle, leaving on a stretcher with exhaustion as the Koreans set up a meeting against either Iran or Iraq in the last four.

"There was big pressure on us," South Korea coach Uli Stielike told reporters after coaxing his team of walking wounded to a fourth straight win. "If we'd lost, we would have been on the plane home and face a lot of criticism." Injuries had already ruled out winger Lee Chung-Yong and midfielder Koo Ja-Cheol, while superstar Son has yet to fully regain fitness after being floored by a flu bug earlier in the competition.

"No other team has had to show such mental strength and sacrifice as our boys," added Stielike. "To lose two of their leaders and still pick them themselves up. I nearly didn't pick Son because of his illness -- he's still not 100 percent. "I told the players this morning that we are all human and everyone has a shitty day. The problem is getting to 90 minutes and still being ready to push through. The boys played 120 minutes and they were all dead. Now our biggest issue is medical."