Walid El Kharti touched home from close range in the first half and Achraf Bencharki scored twice after the break as Wydad Casablanca secured a place in the CAF Champions League final.
After a goalless first leg, the 3-1 home win over USM Alger at Mohamed V Stadium on Saturday puts the Moroccan club in line for their first continental title in 25 years.
But they had to ensure a heart-stopping last 20 minutes to hold onto their aggregate lead after being reduced to 10 men and then allowing their Algerian opponents back into the game.
Wydad look to be comfortably set for a victory after Bencharki's 54th-minute effort put them 2-0 ahead in the game and overall on aggregate after the first leg ended goalless in Algeria earlier this month.
But two minutes later a second yellow card saw Amine Atouchi dismissed by Senegalese referee Malang Diedhiou and suddenly a window of opportunity opened up for the visitors.
Ayoub Abdellaoui then reduced the deficit to make it 2-1 and game on, offering the Algerian side the chance to qualify on the away-goals rule if they scored again.
It was a stop-start affair for the final quarter-hour with USMA pushing frantically forward at the death.
They had a series of corners in the closing stages only for Bencharki to go to the other end and score to ensure Wydad's progress to the final, bringing great relief to a bellicose crowd.
It will be their third final -- after finishing runners-up in 2011 -- and they will meet either Egypt's Al Ahly or Etoile Sahel of Tunisia in next month's final. That second semifinal, second-leg tie is in Alexandria on Sunday night.
