كتب : Hatem Maher
The Egyptian forward was introduced instead of Swiss striker Alexander Frei on 76 points and he needed just three minutes to make a vital impact.
Tamas Hajnal's miscued shot from inside the area found Zidan, who superbly tricked his challenger before firing a low shot past the keeper.
An own goal by Habib Bellaid six minutes from time ensured Dortmun'd precious win.
Zidan, who joined Dortmund from Hamburg last summer, took his tally to six league goals, four behind the team's top scorer Frei.
The 27-year-old ended an eight-match goal drought as his last strike was against Schalke on February 20th.
Jurgen Klopp's side boosted their hopes of earning a place in the Europa League, the UEFA Cup new version.
They lie sixth in the 18-team table on 52 points, two behind fifth-placed Hamburg, who face Hertha Berlin on Sunday.