Dusan Savic had given Pakhtakor the lead after just three minutes with the aid of a healthy deflection but the home side soon levelled through Hawar Mohammed's deflected free-kick.
Farhad Majidi took advantage of a bad error by Pakhtakor keeper Temur Juraev to score his second goal of the tournament in the 22nd minute and substitute Mehdi Seyed Salehi's header early in the second period from Javad Shirzadeh's pinpoint cross extended Esteghlal's lead .
Pakhtakor substitute Sanat Shikov set-up a nervy finish with a late goal for Pakhtakor but Arash Borhani finished off a powerful run with a clinical finish in stoppage time to make the points safe.
"I myself haven't seen Esteghlal playing such attacking football for a long time,” said Mazloomi.
"We saw nice, attacking football from both teams and Esteghlal won the match using their high potential.
"We scored four goals today but with all respect we could have scored four more. Although they were physically strong and using tall defenders, my players played very well against them."
The victory lifts Esteghlal level with Al Nassr in Group B on four points, three behind leaders Al Sadd, and Mazloomi feels the Iranians are now in a strong position to reach the last 16.
"We will absolutely qualify to the next stage if we can grab five points from the second half of matches,” he added.
“However we know our matches against Al Nassr and Pakhtakor will be tough for us and we should never think that we can easily beat Al Sadd.
“Pakhtakor were a strong and difficult opponent for us and we are aware that we are going to have a hard match in our second leg against them."
It was not all good news for Mazloomi, however, as goal scorer Majidi was forced off injured while Esmaeil Sharifat also picked up a knock.
“Majidi was unlucky because he injured his groin muscle again and Esmaeil Sharifat injured his teeth. We have to wait until tomorrow to see whether they can train or not,” the Esteghlal boss said.
Pakhtakor coach Ravshan Khaydarov felt his side's inexperience cost them the game.
"Both teams played attacking football which the spectators enjoy," he said.
"We started very well so that we could score the first goal but because of a lot of mistakes from us, we conceded goals and lost the match in the end.
“Being inexperienced and not old enough were the two reasons for our defeat. We had two 17-year-old players in our team today."
"I can assure you if we had experienced players today, we could have won the match. In our next match against Esteghlal we will be the winner because we are now acquainted with them and we can grab the victory."