South Korea's Yoon Bit-ga-ram (obscured) celebrates his goal with members of his team during extra-time of their 2011 Asian Cup quarter-final soccer match at Qatar Sports Club stadium in Doha Jan  22, 2011. [Photo/Agencies]

DOHA, Qatar - Australia beat defending champions Iraq to reach the Asian Cup semifinals for the first time on Saturday while South Korea downed Iran to move one step closer to its third title.

Both matches were tense encounters that were decided in extra time. Australia avenged a loss to Iraq in the 2007 group stage when Harry Kewell headed in the winner with three minutes to go in extra time.

South Korea also kept its fans waiting, with substitute midfielder Yoon Bit-garam scoring with a left-foot drive from just outside the area in the 105th minute.

Australia now plays Uzbekistan and South Korea faces archrival Japan on Tuesday.

Australia and Iraq appeared to be heading for penalties when Matt McKay's cross found a streaking Harry Kewell, who headed it past Iraq goalkeeper Mohammed Kassid in the 117th minute. Kewell, who plays for Galatasaray in Turkey, stripped off his jersey and swung it around in celebration after scoring his 15th international goal and second of the tournament.

"I am very pleased and happy with the team's performance today. We managed to qualify for the semifinals which is definitely a great achievement," Australia coach Holger Osieck said. "Looking at the game itself, although it went to extra time, in 90 minutes we played solidly in defense ... and created a lot of good chances. If I'm not mistaken, the Iraqis only had one great opportunity and the rest came from half chances. We should have done our job in 90 minutes."

Iraq coach Wolfgang Sidka disagreed, saying that his side had the better opportunities in extra time and was competitive throughout the match.

"You know, it was a very exciting match for both sides," he said. "It was up and down. You saw everything in this game. We always played in front and tried to create chances especially in extra time, in the last 30 minutes. In the end, it was one cross and one header."

In a tight first half, Osieck's plan of subduing Iraq playmaker Nashat Akram paid off, while Sidka's side restricted Australia to half-chances.

The game opened up after the break.

Mohammed missed what would turn out to be Iraq's best chance after he was played in by Younus Mahmood, and that scare appeared to spark Australia into life.

But not until extra time could the Socceroos get the ball in, when Kewell found space between two defenders to power home his header and finally lift the tension hovering over Australia.

"It was important to get the goal, didn't really want to go into a shootout," Kewell said. "(It's a) massive relief. There are no easy games in Asia. We worked hard as a team and I was proud of every one of them."

Iraq defender Basem Abbas, who was closest to Kewell, said the last-gasp winner was hard to accept and he apologized to fans "for not keeping the cup in Iraq."

"It is really painful," Abbas said. "We played a great match and suddenly they scored. It is not anyone's mistake. But I think we could have scored earlier. We had a lot of chances."

In the late game, three-time champion Iran seemed to have the edge going into extra time. But it was the South Koreans - who had appeared exhausted late in the second half - who dug deep.

Their breakthrough came in the 105th when the unheralded Yoon received the ball from midfielder Lee Chung-yong, shifted to his left past two defenders, and then drilled a shot from the edge of the penalty box for the winner.

In the second period of extra time, Iran tried desperately to find space but South Korea crowded its defense and hung on to win. The closest Iran came to tying the match was a shot from Masoud Shoajei with six minutes left in extra time that hit the top of the net.

"The cooperation and the willingness of my players to sacrifice for each other were the key factors of our victory," South Korea coach Cho Kwang-rae said. "Iran has been beyond the level of Asian football, they are close to European level. The main reason we won the match is that we controlled the midfield and didn't let them play their game."