Saudi Arabia's Al Ittihad edged out Ahly in the first game of Fifa's Club World Championship in Tokyo - ending the Egyptians' 55-game unbeaten run.
Mohammed Noor scores the only goal of the game
Mohammed Noor capitalised on an error by keeper Essam El Hadary in the 78th minute to book their semi-final place.
El Hadary flapped at a cross from right-back Ahmed Al Dosari, leaving captain Noor the simplest of finishes.
Ittihad dominated in the freezing conditions, with El Hadary making a smart stop from Mohammed Kallon.
It ends a remarkable run for African champions Ahly, who had been undefeated in all competitions since July 2004.
Asian champions Ittihad's win came despite having three Brazilian players thrown out of the competition the previous day after a Fifa investigation found they were not officially registered with the club.
The Jeddah-based side will now meet Sao Paulo in the semi-finals in Tokyo on Wednesday.
Sydney FC meet Costa Rica's Deportivo Saprissa on Monday - with European champions Liverpool awaiting the winners of that game in the semi-finals.
Al-Ittihad: Zaid, Al Dosari, Tukar, Haidar (Ibraheem 64), Abushgeer (Al Garni 90), Tcheco, Khariri, Noor, Idriss, Kallon, Al Montashari.
Subs Not Used: Al Antaif, Al Sadig, Fallatah, Al Kahtani, Hakami.
Booked: Al Dosari, Kallon, Khariri, Fallatah.
Goals: Noor 78.
Ahly: El Hadari, El Shater (Ashour 71), Ahmed El Sayed, Gomaa, Shawky, Barakat, Motab, Gilberto (Abu Mosallam 45), Moustafa, Mohamed, Abou Treika, Abu Mosallam (Hosni 84).
Subs Not Used: Wabab, El Nahhas, Riad, Hassan, Adel, Flavio, Nader El Sayed.
Ref: Graham Poll (England).