Baghdad Bounedjah (23rd minute), Boualem Khoukhi (26th minute) and substitute Tarek Salman (88th minute) scored for Al Sadd.
It was Al Sadd’s 14th victory, the most by any team. The Wolves also kept their unbeaten streak in tact, the only team to do so thus far in this season’s championship.
Al Sadd now have a 16-point lead over reigning champions Al Duhail, who will face Al Rayyan on Sunday.
Al Ahli remained on 23 points following their seventh loss. They had lost to Al Sadd by a 1-7 margin in the first leg.
Al Sadd were up by two goals going into the half-time break with 64 per cent of the ball. Both goals came through moves along the left flank.
Bounedjah opened the scoring with a quick placing shot, with Nam Tae-Hee giving him the assist.
Defender Khoukhi doubled the advantage three minutes later by heading in Santi Cazorla’s free-kick.
Even as Al Sadd dominated possession, Al Ahli made intermittent moves. One such raid saw Hernan Perez’s shot, off a Nabil El Zhar low cross from the right in the 34th minute, being cleared for a corner. Mohammed Diame came up with a chip shot off the resultant corner kick and it hit the crossbar.
Al Sadd continued to attack in the second half and Guilherme Torres came close in the 69th minute, but his shot on the run went narrowly wide of the left upright.
Both teams made substitutions and Al Ahli captain Omid Ebrahimi, substitute Ali Ghaderi and Hernan all showed greater desire for a breakthrough, which never came.
Meanwhile, Al Sadd added the third goal when Tarek, who came off the bench after 70 minutes, made the most of another substitute Salem Al Hajri’s pass following Cazorla’s corner kick.