The Bulldozer has been out of action since October 14th after injuring his knee in a friendly game against lower division side Shams.
He missed Zamalek's 2-0 victory over Police Union and 2-2 draw with Gaish but was expected to shake off his complaint in time to play against Ismaili.
However, Zaki, at a loss to explain his niggling problems, said he would be forced to sit out Zamalek's match against one of the so-called big three in Egyptian football.
"I'm very sad because I could not fully recover from the injury. I will not be able to play in the next game," he told FilGoal.com on Friday.
"I might travel to Germany to find out the exact reasons for the recurring knee pain I feel."
Zamalek made light of Zaki's absence to overcome surprise package Police after producing a ruthless attacking display, thanks to the skills of attacking midfielders Shikabala and Mohamed Ibrahim.
But they appeared in need of a reliable striker against Gaish after Ahmed Gaafar, who played as a lone frontman, struggled to make his presence felt.
The towering striker was easily thwarted by Gaish defenders, who could have probably faced more threats had the energetic and combative Zaki played.
Zaki, Egypt's main striker, returned to Zamalek in the close season after ending a brief loan spell at English side Hull City.
He made a fine start to the season, scoring three league goals before picking up the knee injury.