Esteghlal reached the semi-finals of the Asian Club Championship with three late goals over a spirited Al Kuwait side whose defeat kept alive the qualification hopes of hosts Al Wahda.
After two draws, a win for Al Kuwait would take them to the semi-finals and render Al Wahda's later match with Nasaf Karsi irrelevant for the UAE champions.
With five players, including national team defenders Khalid Al Jarala and Khalaf Owieid, not making the trip to Abu Dhabi, the inexperienced Al Kuwait side was dealt a further blow with the suspension of defensive midfielder Bander Al Kandari and right-back Razzam Al Abbasi.
The mettle of their reserve back line was tested as soon as Hajjar Basel whistled for the Iranian champions to start the match.
But despite almost relentless pressure and a 5th minute reminder of the aerial threat offered by Mahdi Hasheminasab, Esteghlal created few clear-cut chances in the first half except when Faraz Fatemi came agonisingly close to opening the scoring in the 28th minute.
Taming a left wing cross superbly with his chest inside the box the Esteghlal forward made the most of a slip by Guye Baye Ndiaja to set up a shooting opportunity.
After side-stepping the grounded Senegalese defender, Fatemi unleashed a powerful low drive which beat Al Kuwait 'keeper Ahmad Ben Haji but not the right upright as the post denied the Esteghlal front man has third goal of the quarter-finals.
With the action concentrated in Al Kuwait's half Esteghlal 'keeper Parviz Boroomand had an uneventful 45 minutes with only a weak 14th minute Faraj Laheeb strike testing the Iranian international.
"It was very important for both sides to control the first 45 minutes," said Esteghlal's victorious coach Mansour Pourheidari.
"We knew Al Kuwait needed the win otherwise they couldn't qualify for the semi-finals," he added.
While Laheeb's early effort didn't trouble Boroomand too much it should have served as a warning that Al Kuwait - who needed all three points to guarantee their place in the semi-finals - were dangerous on the counter-attack.
Five minutes into the second half Laheeb gave them a further warning with a powerful shot which Boroomand did well to save at his near post.
Fourteen minutes later Al Kuwait threatened again. Collecting Jarah Al Ataiqi's short corner, the skilful Eid Al Mutairi skipped past two Esteghlal defenders and whipped in a dangerous cross.
However, the ball from the Al Kuwait captain had too much pace for Khalaf Al Mutairi whose shot went wide of the mark.
Esteghlal learned their lesson and after Sohrab Bakhtiarizadeh stung the palms of the Al Kuwait custodian with a venomous 25-yard free-kick, substitute Alireza Akbarpour got the goal that settled the Esteghlal - and Al Wahda - nerves.
The midfielder easily passed a tiring Samy Al Shishiny and charged towards the touchline. Perhaps anticipating the cross Haji was off his goal line allowing Akbarpour to drill the ball past him at the near post.
"We are not used to playing three games over five days and was lost energy at the end," said Al Kuwait's German coach Rainer Bonhof. "When you lose energy, you lose concentration, and that is what happened at the first goal. After that we lost belief in ourselves which is also why we lost the match."
Esteghlal confirmed their ticket to the semi-finals in the 80th minute through Fatemi. Alireza Vahedi Nikbakht jumped strongly to head Mohammad Navazi's corner in to the path of Fatemi who struck the ball past Haji for number two.
Al Kuwait had given a good account of themselves and Esteghlal's third goal was rough justice on the Arabs.
Navazi's tantalising 85th minute cross from the right was headed on by Fatemi and while his header appeared to by deflected into the net by Eid Al Mutairi, the forward claimed - and was credited - with the goal.
"I am proud of our three performances," continued Bonhof. "We were a little bit unlucky in our first two games but we are a young side and this tournament was a great experience for the players."