Ahli face Esperance in the second leg of the competition's semi final away from home, having beaten the Tunisians 2-1 at Cairo Stadium two weeks ago.
Zamalek fans are likely to be divided over whether to support Ahli or hope they will not be able to add to their six Champions League titles.
Al-Sayed, a Zamalek fans favorite who came through the club's youth ranks, chose to back Ahli in their African bid.
"I want Ahli to win, I have many friends there," the 33-year-old, who is reportedly a long-term target for the Red Devils, told FilGoal.com few hours before the anticipated clash.
"Ahli are also representing Egypt. If they win, they will confirm the country's supremacy in African competitions."
Al-Sayed won Africa's premier club competition once when Zamalek beat Morocco's Raja Casablanca in the 2002 final to lift the trophy for the fifth time in their history.
During that game, numerous Ahli fans were in the stands of Cairo Stadium to support their bitter foes, a trend that is nowhere to be seen now.
"I hope that Ahli will win the competition to increase the number of African titles won by Egyptian teams. Such a victory will also lead to another glorious participation in the Club World Cup," Al-Sayed added.
"Regardless of my love to Zamalek, I'm confident that Ahli players can remove tonight's obstacle."
Zamalek striker Amr Zaki also said before the first leg he wished Ahli would beat Esperance.