Ahly failed to capitalize on Zamalek's slip-up after conceding a late equaliser in a 1-1 draw at home to Gouna in the Egyptian Premier League on Friday.
After a turgid first half ended goalless, substitute Taher Mohamed Taher injected life into the game by putting Ahly in front in the 57th minute.
Although the Red Devils wasted a couple of chances to kill off the game, they needlessly eased off in the latter stages and were duly punished as their ex-defender Mohamed Naguib headed home with four minutes remaining.
The draw denied Ahly a third consecutive league victory as they remained second in the table with 37 points, three behind leaders and arch-rivals Zamalek, who played two games more.
Had Ahly defeated Gouna following Zamalek's 2-2 draw with Arab Contractors on Thursday, they would have had the chance to pull six points clear on top of they win their matches in hand.
Gouna, who are managed by former Ahly forward Reda Shehata, lie ninth in the table on 25 points.
Chances were few and far between in a dull first half as Ahly, who are still missing several key players due to a string of injuries, lacked spark in the final third.
Their only opportunity fell to winger Hussein El-Shahat, whose half-volley on the turn narrowly missed the target.
The introduction of Taher and in-form playmaker Magdi Afsha gave Ahly much-needed impetus and the former opened the scoring with a long-range shot that took a slight deflection, bounced in front of the keeper and nestled into the bottom corner.
Afsha then struck the post with a curling shot from the edge of the area and El-Shahat chipped over the bar when played clean through.
When Ahly took their foot off the gas pedal, Gouna pushed forward and secured a share of spoils when Naguib sent a glancing header home after a free kick was floated into the area.
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