The Dervishes tightened their grip on the match shortly after the kick- off, when Mohab Saied bagged a brace on 9 and 20 minutes.
Belal Diziri pulled one back for the visitors eleven minutes later, before Mostafa Karim added the third 15 minutes past the hour mark.
Now a draw or even a 1-0 loss in the second leg, which is taking place in a fortnight, would be enough for the coastal club to qualify for the next round.
Eventful Affair
The match started off at a cracking pace, with the home side piling the pressure upfront.
Ismaili's attacking strategy paid dividends in no time, as Saied opened the scoring after latching on to Karim's deft pass to go one-on-one with the Algerian side's keeper.
The 21-year-old doubled the lead for his team eleven minutes later after exchanging passes with Omar Gamal to penetrate the penalty box and strike home.
On the half-hour mark, Alger's Diziri cannoned a long-range free-kick that found the left corner of Mohamed Sobhi's net.
The away side could have canceled out Ismaili's slender lead afterwards from a penalty-kick, but Ricardo's men breathed a sigh of relief when it was squandered.
Iraqi ace Karim restored his team's two-goal cushion when he connected with a left-wing cross and lashed clinically.