Ulsan are now on a seven-match winning run since landing in Doha. They topped their group with 16 points before knocking out A-League side Melbourne Victory with a comfortable 3-0 win in the Round of 16 fixture last week.
Meanwhile, Vissel will have to improve their play if they are to challenge Ulsan for a place in the Asian Champions League Finals. The J1 League side were underwhelming as they defeated a 10-man Suwon Samsung Bluewings on penalties in their last-eight match.
Vissel lacked creativity without injured playmaker Andres Iniesta and hardly threatened Suwon who fielded just 10 players for more than 80 minutes of the game. In fact, they were lucky to take the game to the tiebreaker as Suwon had the better of chances during the 120 minutes played.
With Iniesta expected to miss the semifinals as well, Vissel have to keep the Ulsan attack quiet while trying to find a way past their rock-solid defence. The winner of the tie will advance to the final where they face Iran's Persepolis FC who booked their spot in October.
Junior Negrao hits top gear as Ulsan vanquish Beijing
Ulsan might have been the highest scoring side in the competition going into Thursday's quarterfinal against Beijing, but one thing that has been worrying Kim Do-hoon in Qatar has been the form of striker Junior Negrao who has been surprisingly silent since the ACL restart.
The 33-year-old emerged as the leading scorer in South Korea's top flight in 2020, but his meager return of two goals in six matches in Asia could have been a major stumbling block for Ulsan if it wasn't for the play of Bjorn Johnsen and Yoon Bit-garam.
The Brazilian striker proved his doubters wrong in the crucial last-eight clash by scoring both goals in the win. This will be Ulsan's first semifinals appearance in the Asian Champions League since winning the title in 2012 under then coach Kim Ho-kon.
While Beijing dominated most of the game -- possessing the ball for 63% of the match -- Junior's individual brilliance is what titled the tie in Ulsan's favour.
Junior won and converted the penalty in the 21st minute to pull his side into an early lead. His acrobatic volley hit the hand of defender Kim Min-jae at close quarters and the referee awarded a penalty after checking the pitchside monitor. He then stunned the sturdiest defence in the tournament by scoring from 30 yards out to seal the win for Ulsan before the half-time break.
Agony for 10-man Suwon as Vissel squeeze through on penalties
It was heartbreak for Suwon in the other quarterfinal clash as they fought with 10 men for the major share of the tie against Vissel. The Bluewings were knocked out after losing the penalty shootouts and ended their hopes of a second semifinal appearance in three seasons.
The two sides had already met in the group stages with Vissel and Suwon winning one apiece. But it was the latter who took the early advantage in the knockout tie as Park Sang-hyeok headed them in front in the seventh minute.
Vissel were largely on the periphery until the referee pointed to the spot after Kim Tae-hwan fouled Daigo Nishi. Though relieved by VAR overturning the penalty decision after finding the foul had occurred outside the box, Suwon still had to pay for it with Kim getting a red card after the foul.
Suwon's misery escalated when Kyogo Furuhashi squeezed the free kick under the wall and into the goal to even the score. Though Douglas came close to pulling Vissel ahead, Suwon did well to keep the score at 1-1 and force the extra time.
Vissel began the extra time on front foot and Suwon's Yang Sang-min had to clear off the line after Furuhashi squared the ball for Douglas with the goal gaping. With no signs of a breakthrough, Iniesta was brought on for the final seven minutes, but it was Suwon who went closest in the dying moments.
With four minutes left on the clock, Suwon captain Kim Min-woo's effort was cleared off the line before Ko Seung-beom hit the post on the follow-up. But, Jang Ho-ik's miss in the shootout proved costly for the South Koreans as Noriaki Fujimoto sent Vissel through to the last four.