Alireza Jahanbakhsh's last-minute penalty gave Iran a 2-1 win over Japan, and a semi-final against Asian Cup holders and hosts Qatar will be their reward.
Jahanbakhsh kept his cool in the 96th minute to keep three-time Asian Cup winners Iran on course for a first title since 1976.
Iran came from behind after Hidemasa Morita put pre-tournament favourites Japan ahead in the first half of an entertaining quarter-final at Education City Stadium.
But Mohammad Mohebi levelled the score in the 55th minute to pave the way for Jahanbakhsh's late heroics.
Iran's win was made even more impressive considering they were without star striker Mehdi Taremi, who was suspended.
Qatar, meanwhile, are in with a chance of retaining the title after they defeated Uzbekistan on penalties following a 1-1 draw at Al Bayt Stadium.
Utkir Yusupov's own goal put Qatar ahead midway through the first half, but Uzbekistan rallied after the break – Odiljon Hamrobekov's effort enough to send the tie to extra time and eventually penalties.
Almoez Ali and Almahdi Ali both failed to convert for Qatar in the shoot-out, but Jaloliddin Masharipov's miss set the stage for Pedro Miguel to be Qatar's hero.
Iran will take on Qatar on Wednesday, a day after South Korea go up against Jordan.