Jovlon Ibrokhimov's first goal of the campaign after just five minutes had handed Bunyodkor the ideal start only for Brazilian striker Rafinha (Rafael dos Santos de Oliveira) to net his fourth goal in three games before half-time on a chilly night in the Uzbekistan capital.

A pair of second-half headers from Korea Republic duo Kim Shin-wook and Lee then handed Ulsan a healthy advantage ahead of next Wednesday's return fixture before Jasur Khasanov hit the post from the penalty spot for the home side inside the final 15 minutes.

Bunyodkor made the ideal start after just five minutes as Slovenian midfielder Jan Kozak pulled a perfectly weighted ball back from the byline to the edge of the penalty area for the on-rushing Ibrokhimov to coolly guide a first-time shot into the bottom corner away from the despairing dive of Ulsan goalkeeper Kim Young-kwang.

The Uzbek champions came close to a second midway through the first half with the Ulsan goalkeeper fortunate Kamoliddin Murzoev's header from point blank range following Viktor Karpenko's inviting right wing cross was straight at the visiting custodian.

Ulsan's first chance of the game soon followed as Rafinha – fresh from scoring three goals in the quarter-final win over Al Hilal – fired straight at Bunyodkor goalkeeper Ignatiy Nesterov.

But Rafinha was not to be denied his sixth ACL goal, and third against Bunyodkor having scored twice for Gamba Osaka in the Group Stage against the Uzbeks in Japan, with the Brazilian rifling the ball past Nesterov at his near post from the edge of the area 14 minutes before the break.

The visitors, though, needed just eight minutes of the second half to take the lead as Kim Shin-wook's front post header from Kim Seung-yong's corner gave Nesterov no chance as the Korea Republic striker netted his fifth goal of the campaign.

And, with 18 minutes remaining, Lee met Kim Seung-yong's flighted free-kick – awarded after Rafinha had been upended 35 yards from goal – and the flicked header looped over Nesterov to double Ulsan's lead.

The home side were handed the ideal opportunity to halve the deficit just four minutes later but Khasanov hit the foot of the post from the penalty spot following a hand ball by Ulsan defender Kang Min-soo.

Kim Young-kwang was then at full stretch to deny Khasanov with four minutes remaining as the Uzbekistan international attempted to make amends as he tried his luck from long range.