Zamalek were handed a surprise 2-1 defeat at the hands of Maqassa, while Ahly beat Wadi Degla to narrow the gap with their arch-rivals to six points in the Egyptian league on Thursday.
In a match that witnessed a couple of highly debatable spot kicks, Zamalek took the lead through a Omar Gaber penalty in the first half, before Ahmed El-Sheikh equalised for the hosts from a free kick after the break.
Maqassa then scored the winner through ex-Zamalek defender Hani Saied from another penalty to deny Zamalek a vital win en route to their first league title since 2004.
In Cairo, a first-half strike from Ramadan Sobhi broke the deadlock for Ahly against Degla in the 13th minute, before striker Amr Gamal made it two on the stroke of halftime.
Nigerian striker Stanley Ohawuchi then pulled one back in the second half, as Emad Meteb restored his side's two-goal advantage in the final minutes.
Zamalek remain on top of the league table with 77 points, while Ahly leapfrogged ENPPI to second place on 71, but the Whites have a game in hand.
Jesualdo Ferreira's men now need seven points from their upcoming five games, after the Portuguese manager had been handed his first defeat at the Cairo giants' helm.
Zamalek looked shaky from the outset, and a defensive blunder could have resulted in a Maqassa early goal if it wasn't for Ali Gabr's last-ditch interception in the first minute.
It then became quite clear that the hosts had the upper hand in the game, exploiting the gaps in Zamalek's midfield and causing their opponents' problems.
As a result, Maqassa's Mahmoud Wahid managed to break clear and go one on one with Ahmed El-Shennawi before the keeper came timely out of goal to force the midfielder to strike high.
But against the run of play, Zamalek took the lead through a highly controversial penalty, after winger Mostafa Fathi had been adjudged to have been tripped on the edge of the area.
Gaber made no mistake sending the keeper the wrong way, to put his side in front in the 28th minute.
Despite their below-par display, Zamalek could have doubled their lead through Ahmed Ali, but the striker's weak shot was cleared off the line by the Maqassa defense just before the break.
Zamalek manager Jesualdo Ferreira made a half-time change, introducing Tarek Hamed in place of Gaber in an attempt to regain composure in midfield.
Even so, Zamalek did not improve much, and a well-deserved goal for Maqassa came just two minutes from the hour mark through substitute Ahmed El-Sheikh.
Ferreira then moved to replace the off-form Tawfik to introduce Ahmed Eid as he changed the formation from 4-3-3 to 4-2-3-1.
But it was just one minute later when Maqassa were in front, with another contentious spot kick handed to the home side this time.
Saied stepped up to take the penalty, beating keeper El-Shennawi this time to give his side their second which then proved to be the winning goal.
Ahly stroll past Degla
After coming close to opening the scoring in the 11th minute through a Hossam Ghaly header, Ahly just needed two minutes later to take the lead through Sobhi.
Following a one-two between Sobhi and Abdallah El-Saied, the former capitalised on some shambolic defending from the visitors to go one ahead.
Right-back Bassem Ali then saw a shot go narrowly wide of the left post, before another full-back in fit-again Hussein El-Sayed squandered a one-one-one chance in the 27th minute.
But it was another fit-again player who made no mistake on the stroke of halftime, and striker Gamal made it two after receiving the ball from Hossam Ashour and sliding past the keeper.
The second half did not witness much of real chances until the 60th minute when Stanley spurned a gilt-edged opportunity from inside the area to pull one back.
The Nigerian, however, atoned for his wasted chance 16 minutes later after going one-on-one with keeper Ahmed Adel before rounding him to temporarily narrow the gap.
But Meteb made sure Ahly restored their two goal advantage later, scoring a trademark goal from inside the six-yard box to make it 3-1, and give his side a glimmer of hope in the league title race.
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