Although Ahly won the Egyptian Premier League title in 12 out of the past 13 editions, Wednesday's triumph was even sweeter given that they appeared off track at the halfway stage.
Zamalek looked frontrunners to be crowned champions for the first time since 2015, opening up a comfortable lead that at some point reached eight points.
But Ahly staged a remarkable comeback to shock their perennial rivals, with some high-profile January signings making the difference as Zamalek failed to maintain their momentum when it mattered most.
Ahly won the title with one match to spare after a 3-0 victory over Arab Contractors gave them an unassailable five-point lead over Zamalek.
"When I took charge of the club [in January] we were far behind, but we were up to the challenge," Ahly's Uruguayan coach Martin Lasarte told ON Sport after the game.
"We were told the situation was difficult, but we are happy with what we have reached now."
A nine-match winning streak in January and February put Ahly on the right track and although they slumped to a 1-0 defeat by Pyramids in April which appeared to derail their title bid, they quickly recovered to assert their authority.
Ahly's rise coincided with a sudden dip in form of challengers Pyramids and Zamalek, with the latter eventually paying the price of opting against renewing the contract of Swiss coach Christian Gross with four matches remaining.
After the departure of Gross, who led Zamalek to the Confederation Cup title for their first African title since 2003, the White Knights veered off the track, with two successive draws against Haras El-Hodoud and Gouna costing them dear.
"This title is special. Where are the people now who kept saying we were out of the race?" said skipper and long-serving midfielder Hossam Ashour, who won his 12th league title with Ahly.
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