A wasteful Zamalek side were held to a goalless draw by minnows Aswan, which ended their five-match winning run in the Egyptian Premier League on Saturday.
Zamalek were denied by the woodwork three times and spurned other goal-scoring opportunities in a one-sided affair, with Aswan defending in numbers to secure a share of spoils.
The White Knights, who also had a goal chalked off following a VAR review early on, failed to score a decisive winner in the latter stages to drop to second in the table with 20 points, behind leaders and defending champions Ahly on goal difference.
Aswan moved up to 11th in the 18-team table on eight points.
Zamalek striker Mostafa Mohamed, back in favour after his talks with French side Saint Etienne fell through, found the net with an angled low shot after two minutes but his goal was disallowed following a VAR review, with Emam Ashour adjudged to have fouled an opponent in the build-up.
The Cairo giants laid siege to Aswan's area, launching a wave after wave of attacks and delivering numerous crosses from both flanks.
Central defender Mahmoud Hamdi headed just wide and against the post while forward Youssef Ibrahim also had a header denied by the woodwork.
At the other end, Aswan could have scored against the run of play on 33 minutes when Mohamed Osama chested down a cross and broke through but Zamalek keeper Mohamed Abou-Gabal palmed away his volley.
It was the same story in the second half, although Aswan appeared more compact at the back.
Ibrahim blasted high over after he was found unmarked by a low cross from the left while the second period's best chance fell to Mostafa Mohamed, whose header struck the bar six minutes past the hour mark.
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