Ahly's hopes of equaling their own record of winning nine successive Egyptian Premier League titles were dealt a serious blow after they lost 1-0 to fellow challengers ENPPI on Tuesday, their third defeat this season.
The Red Devils squandered a handful of goal-scoring opportunities and were punished for their wastefulness when midfielder Mahmoud Kaoud struck with 15 minutes remaining to heap more pressure on the holders' under-fire coach Juan Garrido.
New Nigerian striker Peter Ebimobowei, who joined in the January transfer window, made his debut after being introduced in the latter stages but failed to make an impact as Ahly continued a disappointing run under the Spaniard.
Ahly, who won only once in their previous five matches, could not bridge the gap with leaders Zamalek after playing out a 1-1 draw with their arch-rivals in Thursday's Cairo derby.
Their latest slump allowed second-placed ENPPI to close to within three points of Zamalek, who are on top with 44 points.
Ahly are third with 33 points but they have a game in hand over Zamalek, who are seeking to win their first league title since 2004.
An end-to-and first half did not yield an opening goal despite a flurry of clear-cut chances, including four for Ahly who repeatedly exposed a high ENPPI backline via some deft threaded balls.
Veteran striker Emad Meteb, who is struggling for form this season, was guilty of spurning three opportunities, including a low shot that went just wide and a half-volley which he skewed high over after breaking the offside trap to go clear.
ENPPI were mostly on the back foot but could have also opened the scoring on two occasions.
Midfielder Mahmoud Kahraba, who ended a two-and-a-half year spell in Switzerland with Luzern and Grasshopper to return to Egypt, skipped past Ahly keeper Mosaad Awad after taking advantage of the latter's mis-timed rush out of his goal but his weak effort from a tight angle was intercepted by defender Saad Samir.
ENPPI's Mohamed Nassef also grazed the outside of the post with a powerful shot from outside the area but Ahly regained the upper hand in the latter stages of the first half, wasting further chances.
Winger Walid Soliman superbly held off his challenger after chesting a long ball to go one-on-one but his dinked effort missed the target while Meteb had a close-range effort cleared off the line on the stroke of halftime.
ENPPI had a more cautious approach to the second half but Ahly still managed to create some openings, including a back-post header from winger Islam Roshdi which went narrowly wide..
Midfielder Mahmoud Trezeguet, who had a quiet game, muscled his way into the area on 70 minutes but his effort was thwarted by towering goalkeeper Mohamed Abdel-Monsef.
Ahly were made to pay for the misses five minutes later when Kaoud sliced open the defence after exchanging passes with Kahraba before placing a low shot into the bottom corner.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)