Hassan Mahmoud pulled the Egyptian giants level just before the hour mark, tucking away a cross from the left hand side. But Assale hit the winner for Sewe eight minutes from full time to give the Ivorians a slight edge for the second leg in Cairo next Saturday.
After decades of football success at national team and club levels, this year has largely been a tale of failures for Egyptian sides. The national team created unwanted history by failing for a record third consecutive time to reach the CAF Africa Cup of Nations, a competition they have won an unrivalled seven times.
Ahly had hopes of a record third straight CAF Champions League title dashed by Libyan namesakes Al-Ahly Benghazi in the final qualifying round for the group phase. Fellow Cairo club Zamalek did make the mini-league stage only to fare disastrously, winning just one game out of six and finishing bottom of the table.
Immediately installed as title favourites because of an 18 CAF title pedigree, Ahly found the going tough, scraping past Moroccans Difaa El-Jadida on away goals. Head-to-head results enabled them to pip Sewe for top place in a group where the Egyptians won just twice in six outings.
But hints of the Ahly of old were evident in home and away semi-final victories over Cameroonians Coton Sport with Amr Gamal scoring the second-leg winner in Cairo. The three goals of Gamal made him the leading Ahly scorer in the competition this season, but he missed Saturday's game through injury.