"Some Ahli officials kept on publicly saying that we will lose the game for Ismaili's sake," Al-Sheshini told FilGoal.com.
"This put my players under a lot of pressure and that's why they couldn't reach their full potential tonight."
Some pundits and fans are convinced the White Knights dedicated the Dervishes all three points to help them snatch the title from under Ahli's nose.
However, Al-Sheshini strenuously denied that his team lost the game on purpose, saying that such a claim is inappropriate.
"It's really an inappropriate allegation. Zamalek are a big club who have a great history," he told the Cairo club's official website.
Inefficiency
Although Zamalek's performance seemed below-par, Al-Sheshini believes his side got the upper hand throughout the game, citing inefficiency as the main reason behind the defeat.
"It was a good game, but our players were extremely jinxed and wasted all the scoring opportunities they got," he stated.
"They took a stranglehold on the game, especially in the second half, but couldn't translate their dominance into goals.
"Ismaili, however, converted almost all the chances they got in the first period."
Ismaili are now at the top of the league table with 57 points, three ahead of second-placed Ahli.
The Red Devils have three games to go, while the coastal side only have two.
Both teams will face each other in a decisive play off if they remain tied on equal points till the end of the season.
Zamalek remain in sixth place with 38 points, and the defeat, their tenth this term, marked their all-time worst record of losses in one season.