A first-half goal apiece kept scores locked until late in the thrilling back-and-forth contest before Roar defender Mohamed Adnan was ruled to have brought down Kang Minsoo in the area during the 72nd minute, with Ulsan captain Kwak Tae Hwi burying the spot kick.

The result gives Brisbane two losses and two draws to sit bottom of their ACL group with only two games remaining.

Further heightening the pain for the Brisbane fans was a cracking right-foot strike from substitute Luke Brattan that was denied by the crossbar just moments before Ulsan's game-winner.

Brisbane showed their renowned fighting spirit until the last, creating chances all the way into injury time, but execution, chemistry and decision-making were never at peak levels, in a disconcerting sign ahead of their Hyundai A-League Grand Final with Perth on Sunday.

Ulsan's opener came with a brilliant left-foot finish from Brazilian import Juan Velez in the 11th minute, who dispossessed Mitch Nichols in the Brisbane half and turned quickly to lash past Michael Theoklitos from 25 yards out.

Brisbane's equaliser came after fifteen minutes of hard goal-chasing, when Massimo Murdocca made space on the left and crossed deftly, his ball deflecting into goal off the arm of an Ulsan defender.

Both sides had multiple chances to increase their total in the first half as the attacking action flowed end to end, with desperate defence and ineffectual finishing foiling some enterprising attack.

The final 20 minutes of the game were played at maximum tension, featuring several angry exchanges between groups of opposing players and some highly agricultural slide tackling.

Ulsan's Lee Kuen Ho was the most threatening of the visitors throughout the contest, rattling the cross bar with a long-range drive early in the second half after going close on multiple occasions in the first, including a scoop over the crossbar from close range in the 21st minute.

Brisbane were able to create space to attack on both flanks through the encounter, but the experienced Ulsan side were often able to bottleneck play in the corners and stop the Roar finding the cutback pass to players in a position to capitalise.

Besart Berisha showed the hosts were fired up for the second half, earning a yellow card before play re-started for directing firm words at the referee for allowing Ulsan to stay in their huddle while the Roar were ready to begin play.

Broich was chopped down on the edge of the area twice in the opening five minutes of the second half, but the set-play execution was lacking and Ulsan cleared comfortably on both occasion.

Brisbane Roar: 1 (Own goal 25)
Ulsan Hyundai: 1 (Juan Velez 11, Kwak Tae Hwi 73p)