كتب : Hatem Maher
The Dervishes dominated the first half in terms of possession but rarely tested Police keeper.
They came close just once when Mostafa Karim's low shot went just wide of the post in the 15th minute.
A dreadful error, though common, by Sobhi gifted Police the lead two minutes before the break.
The 27-year-old grasped at thin air to allow Mahmoud Al-Nadi head home a left-wing cross.
Ismaili piled on pressure in the second period but failed to break through a tight Police defense.
The visitors relied on counter attacks that helped them put the result beyond doubt three minutes from time, thanks to another mistake from Sobhi.
He needlessly rushed out of his goal to allow substitute Hamdi Seif lob him the keeper from outside the box.
Ismaili coach Ricardo, who took over at the club last month in a bid to turn around the team's fortunes, will have to find a replacement for Sobhi if his side are to compete for honors this season.
The three-time Egyptian champions slipped to fourth place in the league table with 16 points. Newcomers Police are still struggling, lying second from bottom on eight points.