A depleted Ahly side missing a handful of key players slumped to their first defeat of the season after losing 4-3 to Ittihad of Alexandria in a thrilling Egyptian Premier League game in Cairo on Sunday.
Razak Cisse, a 19-year-old Ivorian forward who is on loan from Zamalek, produced a man-of-the-match display, creating three goals as Ittihad caused an upset at Al-Salam Stadium.
An own goal from Ayman Ashraf gave Ittihad the lead but Egypt striker Marwan Mohsen restored parity with a close-range header, only for striker Khaled Kamar to put the visitors ahead again five minutes before the interval after some great work from Cisse.
In an equally exciting second half, Ivorian midfielder Didier Kore converted a penalty to make it 3-1 but Walid Soliman narrowed the gap with a deft header just past the hour mark.
Substitute Ahmed Al-Alfi struck the fourth two minutes from time but Ahly's youngster Mohamed Sherif curled home on the turn in stoppage time, leaving Ittihad to suffer a few nervous moments.
Ittihad secured their first win over Ahly in four years but the Red Devils will lament a string of injuries that hit their key players, including influential Tunisian left-back Ali Maaloul, central defender Saad Samir and Moroccan marksman Walid Azaro.
Ahly, who will be looking to protect a 2-0 advantage when they face Algeria's ES Setif in the second leg of the African Champions League semi final on 23 October, lie ninth in the table with 11 points, six behind Zamalek who played two matches more.
Ittihad moved to the sixth spot with 14 points from 10 matches.
Despite their injuries, Ahly were the dominant side in the early exchanges, squandering two clear-cut opportunities in the first 11 minutes.
Mohsen side-footed just wide with the goal at his mercy after being picked out unmarked by a long ball and winger Ahmed Hamoudi also missed a sitter shortly after.
Ittihad scored against the run of play in the 19th minute when Cisse's low cross was converted into his own net by the sliding Ashraf, an Egyptian international defender.
Mohsen brought them level following a defensive lapse on 30 minutes, heading home past an advancing keeper after a cross from Ahly's own half by Malian defender Salif Coulibaly eluded the entire backline.
But Ittihad regained their lead in the 40th minute following a brilliant individual effort from Cisse, who skipped past three challengers in the area to cross low for Kamar at the far post to easily tap in into an empty net.
Ahly were further stunned nine minutes after the break when Hamoudi clumsily tripped left-back Mohamed Nassef in the area and Kore made no mistake from the spot, sending the keeper the wrong way.
The in-form Soliman kept their hopes alive with a fine glancing header from an Islam Mohareb cross in the 61st minute but Ittihad restored their two-goal cushion with two minutes remaining in what seemed a killer blow to Ahly's hopes.
Substitute Al-Alfi drilled home from another center from Cisse, who stole the show after producing a display that might prompt Zamalek, Ahly's bitter Cairo rivals, to consider recalling him next season.
Ahly youngster Sherif, who came on in the dying minutes, curled a low shot into the bottom corner in stoppage time but Ittihad held on for a remarkable victory.
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