Al-Ahly are chasing a record third consecutive title, but failed to get an away goal that would have given them a real advantage heading into the return fixture in Cairo on November 9.
Etoile are chasing a first ever continental crown having been losing finalists in 2004 (against Enyimba of Nigeria) and 2005 (Al-Ahly), and know that a score draw will be enough to get them home.
Al-Ahly coach Manuel Jose is certainly cautious ahead of the second leg, in stark contrast to his players, who celebrated wildly at the final whistle in Sousse as if they had the trophy in the bag already.
_quote"It would be ridiculous to think we won the cup because we drew in Tunisia," Jose told BBC Sport.
"Both teams still have a 50-50 chance. I have to admit that we concluded our target in Sousse but we still have to work very hard to make sure that this cup stays with us.
"Etoile are a very good team and honestly they deserve all the respect. They have some very good young players and they are certainly a tough challenger."