The teams were going head to head at the quarter-final stage of the continental tournament for the fifth successive edition and once again it was a typically closely-fought affair.

As in 2007, neither side could break the deadlock inside 90 minutes but Yoon ensured penalties would not be needed when he struck from the edge of the area in the last seconds of the first period of extra time.

The victory for the South Koreans sets up the enticing prospect of a semi-final clash with east Asian rivals Japan on Tuesday.

The strength of Cho Kwang-rae's side lies in their speed and they were certainly quick off the mark in the match as the won a free-kick after just two minutes, but Celtic midfielder Ki Sung-yueng could only send his effort into the wall.

Ki again threatened after 13 minutes when he sent a powerful volley just wide before Celtic team-mate Cha Du-ri failed to produce the shot his rampaging run into the box deserved as he scuffed an effort harmlessly wide.

Iran had largely been quiet but perhaps came the closest of either side to opening the scoring midway through the half when Ji Dong-won almost headed Mohammad Reza Khalatbari's free-kick into his own goal, but keeper Jung Sung-ryong did well to push away the danger.

Park Ji-sung had a half chance soon after the restart when he tried his luck from outside the area but his shot was deflected wide by an Iran defender.

Mahdi Rahmati had to be alert in the Iran goal when Ji headed straight at the stopper from close range after the South Korea forward had risen to connect with a fine Cha cross.

But it became clear as the half wore on that the two sides were not going to be separated inside 90 minutes and so it proved as Pejman Nouri's lashed shot signalled the last effort of normal time.

They continued to cancel each other out in extra time and it looked as though penalties would be needed to determine a winner before Yoon was allowed to run to the edge of area and the midfielder dispatched a powerful shot into the back of the net.