In what was billed as the biggest match of the round between the reigning champions and three-time winners Raja, the Moroccans were forced to come behind twice in front of their own fans.
Mohamed Benyettou scored both goals for the Algerians, with Yassine Salhi and then Adil Karrouchy keeping the tie alive for Jose Romao's men ahead of the return leg on April 30.
The two other Algerian clubs in action on Sunday, USM Alger and Eulma, both came out victorious.
Sfaxien, under the guidance of new coach Paulo Duarte for the first time in continental competition, were Eulma's visitors and ultimately left trailing 1-0, while reigning domestic champions USM Alger beat Kaloum Star 2-1, though they may come to regret conceding an away goal.
Al-Hilal Omdurman of Sudan picked up arguably the result of the day, claiming a 1-0 triumph at Sanga Balende, taking a huge stride towards progression.
In an otherwise unremarkable encounter, record eight-time champions Al Ahly lost 1-0 to a late Mohsen Yajour screamer against Moghreb Tetouan, while their Egyptian compatriots and debutants Smouha lost by the same scoreline in Congo to Leopards de Dolisie.
