Persepolis recorded a 1-0 victory in their AFC Champions League Group A match against Al Nasr on Wednesday.
After Branko Ivankovic's side were defeated 3-0 in the reverse fixture in Riyadh last month, the Iranians new that a second successive loss to their opponents on the day would see them relinquish first place in the group.
Indeed, Persepolis started the stronger of the two sides and had their first genuine effort at goal in the 18th minute when Ahmad Noorollahi forced Al Nassr keeper Abdullah Al Enezi into a save, albeit an awkward one after the stopper fumbled the initial ball.
Despite having the lion's share of possession, Persepolis were limited to shots from range and in the 30th minute Noorallahi was again on target with a 25-yard drive, although Al Enezi saved more comfortably this time.
The best chance of the opening hall fell to Hamidreza Aliasgari, but his header was saved by the outstretched hand of the Al Nassr keeper.
After the half-time interval, the hosts continued to search for the opener and their efforts were rewarded when the referee awarded a penalty in the 60th minute, following a coming together of midfielder Mehrdad Kafshgari and Al Nassr defender Mohamed Husain.
Mehdi Taremi then made no mistake with his spot kick, flummoxing the goalkeeper with a dinked 'Panenka' kick
The Saudi's had their only notable chance of the game with 15 minutes to play when Ahmed Al Fraidi's cross was met by Poland midfielder Adrian Mierzejewski at the back post but he could only thump his header onto the crossbar.
In the last minute, Mierzejewski went close again, cutting in from the right flank and unleashing a left-footed shot from outside the box, but Persepolis keeper Sousha Makani made no mistake with the save, pushing the ball out for a corner which resulted in nothing.