Esteqlal defeated Shahin 2-1 at home on Monday to move to the second place, with just one point shy of Sepahan, which had defeated Abumoslem 2-0 on Saturday.
After a goalless first half, Reza Enayati opened the scoring for Esteqlal in the 48th minute and Arash Borhani doubled the lead nine minutes later.
Shahin managed to answer only one of the goals in the 67th minute through Mohammad Ahmadpouri.
Earlier on Monday, Zob Ahan sealed a 2-0 away victory over Moqavemat to stand in the third place, on level points with Esteqlal but on lower goal difference.
Paykan stands in the fourth place with 25 points and Steel Azin is fifth with 24 points, following a decisive 2-1 win over Persepolis on Saturday.