Brazilian striker Rafinha and Korea Republic international duo Kim Shin-wook and Lee Keun-ho scored at Jar Stadium in Wednesday's semi-final first leg in Tashkent as Ulsan recovered from falling behind to Jovlon Ibrokhimov's fifth minute strike.
Ulsan will entertain Bunyodkor in the second leg next Wednesday with the winner earning the right to host next month's final against either two-time champions Al Ittihad or fellow Saudi side Al Ahli.
On Monday, Naif Hazazi scored midway through the second half as Al Ittihad grabbed a narrow advantage in their first leg against Jeddah neighbours Al Ahli.
"I said before the game we would play with an attacking style and the players played aggressively and a 3-1 win makes it a lot easier for the second leg," said Ulsan coach Kim Ho-gon.
"Even though it was a difficult away match the players wanted to win. But even though we have won 3-1, we will make sure we are prepared to play well again in the second match."
Unlike Ulsan who must face Suwon Samsung Bluewings in the K-League on Sunday, defending Uzbek League champions Bunyodkor do not have to contend with a domestic outing before the return fixture at Ulsan Munsu Stadium leaving coach Mirdjalal Kasimov plenty of time to fix the mistakes from the first leg.
"I did not expect such a big defeat. I did not expect we would lose as we started very well and we had our chances," said Kasimov.
"But we handed the win to Ulsan as we made a lot of mistakes. We made many mistakes in defence."
Despite a knee injury putting doubts over his participation in the first leg at Prince Abdullah Al Faisal Stadium in Jeddah on Monday, Saudi Arabia international Hazazi netted his eighth goal of the campaign midway through the first half to hand Al Ittihad the advantage over Al Ahli.
"We made a slow start to the game and Al Ahli were good in the first half while we had a better performance in the second period," said Al Ittihad coach Raul Caneda.
"For the second leg, we will not play defensively and hopefully we can put in a better performance and get a good result in order to make it all the way to the final."
But after having had their chances to score on Monday, Al Ahli are still firmly in contention heading into the second leg which will also take place at Prince Abdullah Al Faisal Stadium in Jeddah on Wednesday.
"In general, we were good in the first half. However, in the second half we lost a lot of possession in midfield and the players tried to play long balls in an unexpected way," said Al Ahli coach Karel Jarolim.
"The second half was totally different to the first half but the match is over now and Al Ittihad won the game.
"However, the result is for one leg only and hopefully we will play better in our next game and get the win in front of our fans."