Asian Cup hosts UAE and Gulf rivals Qatar pulled off titanic upsets as they sent defending champions Australia and Son Heung-min's South Korea crashing out in the quarter-finals on Friday.

Milos Degenek's defensive howler handed UAE a 1-0 win, and the Qataris beat South Korea by the same score to set up a semi-final buzzing with regional tensions because of the Gulf blockade of Qatar.

UAE veteran Ali Mabkhout pounced on Degenek's misjudged back pass for a win that was greeted by joyous drumming and a sea of smartphone torches at Al Ain's Hazza Bin Zayed Stadium.

In Abu Dhabi, Abdelaziz Hatim fired a late winner as 2022 World Cup hosts Qatar stunned title-chasing South Korea 1-0 to reach the semi-finals for the first time.

Japan and Iran, with seven Asian Cup titles between them, will play the other semi for a place in the final in Abu Dhabi on February 1.

Graham Arnold's Australia will feel aggrieved by their defeat after peppering the UAE with 22 shots, only to be undone by Degenek's defensive error on 68 minutes.

Degenek, who this week signed for Saudi giants Al Hilal, rolled a casual ball to Mat Ryan but Mabkhout nipped in and rounded the Brighton 'keeper to score into an empty net.

"Football can be a cruel sport," said a rueful Arnold, backing the 24-year-old central defender to bounce back.

"Obviously he's hurting at the moment but I'll make sure that he's okay. He's a fantastic kid, fantastic professional and he's got a long future with the Australian national team."

Earlier South Korea were looking to end 59 years of hurt after last winning the tournament in 1960, but they missed a string of chances before Hatim's hammer blow after 78 minutes.

"We deserve to be in the semis. I feel like the happiest coach in the world -- it's a big step forward," said Qatar coach Felix Sanchez.

It took the Koreans until three minutes into the second half to register a shot on target, Hwang Ui-jo forcing a low save from Saad Al-Sheeb from the edge of the box.

Lee Chung-yong then blazed wide and captain Son Heung-min was denied by Al-Sheeb before Kim Jin-su's free kick smacked against the post.

That wastefulness came back to haunt them when Hatim smashed a long-range rocket past goalkeeper Kim Seung-gyu to give the 2022 World Cup hosts a famous victory.

"We didn't create too many opportunities but we created more than them," protested South Korea coach Paulo Bento.

In Al Ain, Trent Sainsbury flashed a header over as Australia proved an early threat but UAE were also looking sharper than their previous games.

Apostolos Giannou saw a shot palmed away as Australia finished the first half strongly, but Mabkhout was inches away when his header just cleared the bar.

The second half was one-way traffic as Degenek and Jackson Irvine went close with headers, and Giannou had a goal chalked off for offside.

All Australia needed was a goal and there was disbelief when it went the other way as Mabkhout, a peripheral figure for most of the half, seized on Degenek's back pass.

"We showed a lot of character -- we were strong in defence and attack and we fought well for the entire game," said UAE coach Alberto Zaccheroni, praising Mabkhout whose nine Asian Cup goals place him joint third on the all-time list.

"Everybody knows he's a high-calibre striker... his goal was critical and turned the whole match," said the Italian.