Al-Ahly and their traditional arch-rivals Zamalek are getting ready for their Premier League derby in Cairo on Friday. Both teams will be missing key players. Ahly's midfielder Ahmed Fathi will be sidelined for four weeks with a groin injury, the local media reported on Tuesday. Fathi sustained the injury in Sunday's 1-0 victory over Al-Ittihad, which forced him to limp off after just 14 minutes. The versatile midfielder is likely to miss the rest of the league campaign. He will also miss the CAF African Champions League clash with Ittihad of Libya on April 23. Fathi's teammate Gelberto will also miss the game due to injury, but their teammate Ahmed el-Sayyed is raring to go. Meanwhile, Zamalek's defender Mahmoud Fathallah is hoping to be fit for Friday's clash. The Egyptian international picked up a groin injury during Zamalek's 1-1 draw with Police Union and missed the next game against Harras Al-Hodoud. "I always sustain injuries before important games," he said. "But I will never miss the Cairo derby; I will play irrespective of my condition." Ahly are leading the Egyptian Premier League table with 56 points, nine ahead of Zamalek, who lie in second place. Ahly's coach Hossam el-Badri has been urging the fans to support their team as it's a crucial fixture. If Ahly win, they will mover closer to clinching a sixth successive title. In other news, Petrojet denied Assiut Petroleum their second home win of the season after a thrilling 3-2 Egyptian Premier League encounter Monday night in the Upper Egyptian city of Assiut. Assiut were two goals up thanks to a double from ex-Petrojet striker Hossam Osama, but the relegation certainties failed to preserve their lead. Mohamed Koffi pulled one back for Petrojet in the 65th minute, Ahmed Shaaban equalised 11 minutes from time and Ahed Abdul-Maguid scored the winner in the 87th minute. Petrojet move up to third place with 42 points, five behind Zamalek, while Assiut are rock bottom with 16 points. Elsewhere, Ismaili were held to a goalless draw by Police Union Monday night in Cairo. The Canal-based outfit failed to move to the third place after this stalemate at Police Union, who also missed out on a top-five spot in the same game. Ismaili's goalkeeper Essam el-Hadari made many brilliant saves. With this draw, Ismaili lie in fourth place with 41 points, while Police Union are in sixth with 36 points.