A win for the Cairo Red Devils away to Simba SC of Tanzania -- a side they have already caned 5-0 this month -- would lift them to 10 points from four matches in Group D.
And that total will guarantee Ahly a last-eight slot unless bottom-of-the-table JS Saoura of Algeria end a three-match winless run by overcoming Congolese visitors V Club.
AFP Sport previews matchday 4 of a Champions League restored to 16 clubs after Ismaily of Egypt were reinstated at the weekend when a crowd-trouble ban was overturned.
Recent African champions Wydad Casablanca of Morocco and Mamelodi Sundowns of South Africa can all but seal progress to the knockout phase if they collect maximum points.
Wydad should have little difficulty defeating Lobi Stars of Nigeria in Rabat having already done so in west Africa thanks to a Mohamed Nahiri penalty.
Sundowns were far superior to ASEC Mimosas of the Ivory Coast when winning 3-1 in Pretoria with Argentine debutant Emiliano Tade among the goals.
But Abidjan holds bitter memories for the Pretoria club with their last visit ending in a humiliating 6-1 hiding from Africa Sports, the great domestic rivals of ASEC.
Reigning African champions Esperance of Tunisia have thrown away an advantage over Orlando Pirates of South Africa after bringing forward the Tunis kick-off time by six hours.
Instead of a 2000 local time (1900 GMT) start and cold conditions that Pirates believed could affect their performance, the visitors can expect mild mid-afternoon weather.
Esperance will also lack support at Stade el Menzah with the club serving the second half of a two-match ban over crowd trouble last season.
Should the co-leaders draw, as they did in a cagey Soweto clash this month, Horoya of Guinea can climb from third place to first by overcoming FC Platinum of Zimbabwe in Conakry.
TP Mazembe of DR Congo are away to Club Africain of Tunisia, the team they humiliated 8-0 this month for a record Champions League group-stage victory.
The north Africans reacted to the debacle by claiming the Congolese had drugged them by injecting substances into their food in Lubumbashi.
Five-time African champions Mazembe then pointed out that Africain had chosen their hotel and brought food, water and a cook from Tunisia.
The Congolese said they expect "fair play" in Rades, a plea they hope will be heeded by the often troublesome supporters of Club Africain.
Ahly banged five goals past Simba in Egypt despite lacking nine potential first choices, including loanee Ramadan Sobhi from English Premier League strugglers Huddersfield Town.
But the Egyptians need only check the record books to know the return match in Indian Ocean city Dar es Salaam may be far more difficult -- they lost 2-1 there on a previous visit.
After successive five-goal beatings, Simba hope Meddie Kagere and Clatous Chama can rediscover the form that delivered nine goals between them earlier in the competition.
Saoura came from two goals down to hold V Club in an intimidating Kinshasa fortress and maximum points at home against the Congolese would throw open the race for second place.