Esteghal went in to the Round 21 clash at the Hafezieh Stadium looking to bounce back from Sunday's 1-0 defeat at the hands of lowly Mes Kerman but fell behind with ten minutes played with Fajr skipper Mehdi Rajabzadeh opening the scoring.
Mojtaba Jabari drew Esteghlal level ten minutes later but the Tehran giant were to succumb to their fifth defeat of the season when ex-Zob Ahan midfielder Mehdi Rajabzadeh scored the winner six minutes from time.
Esteghlal will face Rajabzadeh's former employers on February 10 when the Tehran giants host Zob Ahan in the first match of the playoff stage for the latest edition of Asia's premier club competition with the team that emerges victorious taking on Saudi Arabia's Ettifaq for a place in Group A of the 2012 AFC Champions League.