Kick-off was delayed by 25 minutes because of pre-match clashes between rival Al Ahly supporters but that did not deter the reigning champions, who secured a 37th-minute lead through Abdalla El Said.
Al Ahly continued to put the pressure on their Congolese opponents and it eventually told on 68 minutes when Waleed Soliman, the architect of the first goal, converted Mohamed Aboutrika's assist.
Leopards fought valiantly to get back into the contest and pulled a goal back through Sidoine Beaullia six minutes from time but could not manage an equaliser.
The result means Al Ahly draw level on points with group leaders Orlando Pirates of South Africa, who have superior goal difference and a game in hand.
ES Tunis remained top of Group B after a 1-0 home triumph against Ivory Coast's Sewe Sport.
The Tunisians scored the solitary goal in the 58th minute through Anther Yahia.
Having played an extra game than second-placed Cotonsport, ES Tunis now has a three-point advantage on top of Group B with a superior goal difference.
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