Ghanaian striker Yaw Annor opened the scoring for Ismaily in the 19th minute when he was found unmarked at the far post to slot home from close range.
Senegalese forward Ibrahima Ndiaye restored parity in the 38th minute after being set up by Samson Akinyoola inside the box.
But unfortunately for the White Knights, Ashraf had the final say as he scored in his own nets while attempting to clear a ball from his area in the 58th minute.
The result leaves Zamalek trailing at the fourth place with 43 points after 26 games. The White Knights are currently ten points behind leaders Ahly, who have played five games less.
The defending Champions need to climb up the table to finish in the top two when the season ends in August to secure a Champions League spot or at least secure a top four finish to qualify for the Confederation Cup, Africa's second tier competition.
Meanwhile, Ismaily boosted their chances of survival, climbing to 14th in the table with 29 points, widening the gap with four points above the relegation zone.
Zamalek will face Aswan in the 28th matchday of the Egyptian Premier League on Thursday.
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