Hot on the heels of last weekend's 2-0 home reverse to Saipa, Zob Ahan went down by the same scoreline at third-placed Sepahan.
Hadi Aghily opened the scoring from the penalty spot nine minutes before half-time and Milorad Janjus added a second nine minutes after the interval.
Esteghlal took full advantage of the leaders' slip-up, winning 3-1 at second-bottom Peykan.
First-half goals from Gholam Ashoobi and Seyed Seyedsalehi put the visitors in the ascendancy and Hanif Omranzadeh sealed the win 10 minutes from time - four minutes after Jahangir Asgari had halved the deficit.
Karrar Jassim was the hero for fourth-placed Teraktor Sazi FC, scoring both goals in their 2-1 home win over Shahin FC.
Jassim gave the hosts the perfect start by making the breakthrough in the seventh minute and, after Abbas Porkhosravani had equalised before the break, the Iraq forward struck again four minutes from time to seal the win.
Mes stayed fifth after Edinho's early strike proved enough to see off basement boys Steel Azin FC 1-0.
Naft Tehran boosted their survival hopes with an emphatic 4-1 victory over fellow strugglers Pas-Hamedan.
Marcio Narciso and Josiesley Rosa put the hosts in control with first-half goals and Rosa's second and a Ramin Khosravi own goal after the break extended their advantage before Morteza Aziz Mohamadi pulled one back.
Kaveh Rezaei's second-half equaliser earned Foolad a 1-1 draw at Saba Battery, who had taken a 26th-minute lead through Farzad Hatami
Saipa and Malavan also drew 1-1, Mehrdad Oladi striking four minutes from time to cancel out Reza Khaleghifar's opener.
Sanat Naft and Shahrdari Tabriz FC remained just above the drop zone after sharing a 1-1 draw.
Carlos Ataliba's goal on the half-hour had the visitors in front before Rasoul Navidkia restored parity three minutes into the second half.
Finally, sixth-placed Perspolis and Rah Ahan battled out a goalless draw.