FilGoal.com understands that Henri Michel has been mooted as a possible successor to Decastel, who came under fire of late.
Frenchman Michel had a short spell at Zamalek over two years ago, but he left all of a sudden ahead of the 2007-2008 season.
"Zamalek have already opened talks with Michel," a reliable source, who spoke on condition of anonymity, told FilGoal.com.
"He will arrive in Cairo to complete the negotiations should Zamalek relieve Decastel of his duties."
Former Ivory Coast manager Michel, who also managed Cameroon, Morocco, Tunisia, UAE and Raja Casablanca throughout his career, was tipped more than once to get back to the Cairo side last season.
However, his return never materialized.
Meeting
Zamalek's board members are set to convene in the immediate future to go through the reasons behind the team's inconsistency.
Swiss tactician Decastel has been appointed as the five-time African champions' boss since last winter, and he made a good first impression by helping Zamalek end their recurring losses at the time.
But now the club's board is questioning his ability to keep the team on an even keel.
"The first team's problems will be discussed during a meeting on Friday, and the board will decide whether or not the current technical staff will stay on," official Tarek Hashish said.
Zamalek have been stumbling over the past five years, having claimed only one trophy in the Egyptian Cup in 2008.
After incumbent president Mamdouh Abbas took the helm this summer, he invested significant amounts of money in landing high-profile players.
But his attempt to turn around the club's fortune has yet to be proven successful.
Zamalek had a promising start to the season by outclassing ENPPI 3-1 in the Egyptian Premier League, but then lost 2-1 to Petrojet and salvaged a 2-2 draw with Arab Contractors.