Former coach Vahid Halilhodzic (70) cut him out of the team in a dispute over his willingness to play, but when the Bosnian was sacked in August, his replacement Walid Regragui (47) welcomed the Chelsea player among others back into the Atlas Lions' fold.
Against Belgium, man of the match Ziyech showed what the team was missing in a brilliant performance that helped Morocco to their first World Cup victory since beating Scotland 3-0 in 1998.
"He is incredible, the spirit he has, coming back to the national team," a jubilant Regragui said.
"A lot of people talk about him, say he is crazy and difficult to manage, that he can't help the team. But when you give him the love and confidence, he will die for you. He is a key player and a different player with the national team."
The former Ajax player's speed was a problem throughout for the Belgian defence and the focus of Morocco's attacks from the right.
Ziyech had seemed to give Morocco the lead just before the break when he fired a free kick into the pack and it bounced past Thibaut Courtois at the near post on the stroke of half time, but the VAR review saved the Devils.
Ziyech had Morocco's first shot on goal in the second half, and was allowed to move freely between the lines in the front third, tormenting the Belgian defence.
Still full of running in the final minutes at 1-0 up, he provided the cross to Zakaria Aboukhlal (22) who clipped it into the roof of the net to seal the victory as the stadium boiled over.
Talk of Ziyech's brilliance must be accompanied by credit to Regragui, the mastermind of Morocco's transformed performances in the last two months.
Regragui, who led Moroccan club side Wydad to the African Champions League title last May, made match-winning changes against the Belgians, including the introduction of Aboukhlal whose second goal killed the game.
Another substitute, Abdelhamid Sabiri (25), struck the shot that touched captain Romain Saiss (32) on its way in for the first goal.
Morocco drew 0-0 with Croatia in their opening game and have not conceded a goal in five matches under Regragui so far, a record he would dearly like to take further into the Qatar tournament.
Check out all the statistics from Morocco's victory with Flashscore.
