|Yoon is congratulated by coach Cho as the Koreans stayed on course for their first title in 51 years [AFP]
Substitute Yoon Bit-garam produced a stunning extra time strike to send South Korea into the Asian Cup semi-finals with a 1-0 defeat of a defensive Iran.
The Koreans dominated territory and possession for long periods at the Qatar Sports Club on Saturday but failed to create many clear cut chances as the Iranians defended deeply but effectively, marshalled by the headband-wearing Hadi Aghili.
However, Aghili and his team could not stop Yoon from cutting in off the right flank and angling a left-foot drive into the far corner of the net in the 105th minute to leave Korean dreaming of a first Asian Cup title in 51 years.
South Korea will now play three-times champions Japan at Al Gharafa Stadium on Tuesday.
Korean coach Cho Kwang-rae predicted the Iranians would resort to fouling in the early stages to disrupt his side from playing their short, sharp passing game, and heavy challenges flew in from both sides in a niggly start.
Teenage striker Ji Dong-won looked the most likely to break the deadlock for the Koreans with Manchester United midfielder Park Ji-sung also causing problems for the three-times champions.
Ji, 19, went close to opening the scoring on the stroke of half time but his curling right-foot effort went narrowly wide.
The start of the second half continued in much the same fashion, despite Iran coach Afshin Ghotbi bringing on defender Khosro Heidari to try and stem the flow.
Ji did well to leap highest to meet a Cha Du-ri cross from the right but the striker's 63rd minute header was straight at Mahdi Rahmati in the Iran goal.
With 25 minutes remaining, Iran started to enjoy more possession and ventured out of their defensive shell with captain Javad Nekounam firing a free-kick just over the bar with 12 minutes left.
The start of the 30 minutes of extra time was littered with stoppages for minor injuries before Yoon, who came on in the 81st minute for Koo Ja-cheol, scored his thumping drive.