A first-half header by striker Ahmed Abdel-Zaher gave Ahly their third consecutive Egyptian Premier League victory after they beat Maqassa 1-0 on Wednesday.
The January arrival scored what proved to be the winner midway through the first half to take his tally to two league goals, having opened his account with Ahly in their 2-1 victory over his former club ENPPI earlier this month.
Ahly's midfielder Ahmed Nabil "Manga" was dismissed for a second bookable offence on 71 minutes and coach Hossam El-Badry was ordered from the touchline shortly after for protesting the referee's decision.
However, the Red Devils preserved their lead to move three points clear of second-placed ENPPI and four ahead of Haras El-Hodoud at the top of Group A.
The top two in Groups A and B will advance to the decisive playoff, where a mini-league with only home fixtures will be held to determine the champion.
Playmaker Abdallah El-Said was unlucky to see his curling free-kick strike the crossbar after 12 minutes but Abdel-Zaher made amends 11 minutes later to put Ahly in front.
Ahmed Shedid, who retained his place in the starting line-up despite the return from injury of veteran left-back Sayed Moawad, floated a deep free kick and Abdel-Zaher rose unmarked to send a glancing header past the stranded keeper.
Abdel-Zaher's strike partner Emad Meteb could have added the second four minutes before the break but his shot on the turn was collected by the keeper.
Chances were few and far between in an uninspiring second half but Maqassa managed to create their first real chance in the 56th minute when Ahly keeper Sherif Ekramy tipped over a powerful header from Tunisian striker Issam Merdassi.
The red-card of Manga hardly affected the display of Ahly, who held out for another win.
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