The decision came one hour after the club’s 2-1 defeat against Ghazl El-Mahalla in a league game on Tuesday.
Mansour added that former Ferreira assistant Ossama Nabih will take charge of the team in succession of the Portuguese coach.
The defending champions struggled in the league since the 2023 start as they failed to earn a single win in five league games.
They also exit the Egypt Cup semis after losing to Pyramids FC on penalties.
The club president said on Sunday that the board had voted unanimously on the sacking of the Portuguese but had decided to postpone announcing the decision to the the sixth of February.
Ferreira, who was appointed as Zamalek new coach in March 2022, helped the club win the domestic double.
During his tenure as coach, Zamalek played 51 games, winning 32, drawing in 11 and losing nine.
Zamalek are now fifth in the league table with 26 points, 11 points behind leaders Ahly.
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