Tractor had the chance to strengthen its position at the top but failed to overcome Sepahan at the packed Yadegar-e Emam Stadium in Tabriz.
Tractor and Sepahan remain first and second with 45 and 44 points, respectively.
At Azadi Stadium, Persepolis defeated Esteghlal 2-1 in the Tehran derby. Hossein Kanaani converted a penalty just before halftime.
Substitute Alireza Kushki equalized with a header in the 55th minute.
Persepolis, needing a win to stay in the title race, restored its lead in the 71st minute through an unmarked Ali Alipour.
Elsewhere, Mes edged Chadormalu 1-0 in Rafsanjan, while Esteghlal Khuzestan lost 2-1 to Malavan in Ahvaz.
On Friday, Foolad will face Zob Ahan in Isfahan, Kheybar hosts Aluminum, Nassaji takes on Shams Azar, and bottom-placed Havadar meets Gol Gohar in Tehran.