Jamal Sellami showcased a strong line-up that included Ben Malango and Fabrice Ngoma. Mazembe went with a solid front-three in Isaac Tshibangu, Jacob Muleka and Rainford Kalaba.
Raja got off to a dream start and it was none other than Malango, who applied a solid finish following a nice move six minutes from kick-off.
The Moroccan giants though were forced into an early substitution a minute afterr going ahead, as an injury saw Abderrahim Achchakir removed for Omar Boutayeb.
Sylvain Gbohouo stunningly prevented the hosts a second with a strong palm off Abdelilah Hafidi's powerful strike 16 minutes gone, with the Ravens on the hunt.
Raja continued pushing for more; however the visitors looked promising on the transition with Kalaba and Tshibangu having Sanad Al Warfali and co defending with their backs to goal.
The side from the Democratic Republic of Congo showed a lot more purpose to the second half, with more firepower off the bench in Mulota Kabangu who replaced Miche Mika.
Mazembe were on the attack 10 minutes into the second half and had the opposing defence on their toes with Tshibangu firing in from close-range.
The Ravens refused to lie down despite having the front-foot and posed a few issues on the counterattack, but Gbohouo marshalled the danger effectively.
Mazembe also caused a few issues on the counter as Joseph Ochaya got on the end of a fast-paced move before flashing wide.
The contest was finally put to bed in the 79th minute after captain Badr Banoun combined with a cross into the area to head home to hand Raja a two-goal cushion heading to next week's second leg in the Republic of Congo.