Wanderers pegged back by Seoul
The holders led courtesy of Kerem Bulut's opening goal early in the Group H clash at Pirtek Stadium but had to settle for a share of the spoils after conceding what was a deserved equaliser for the hosts, scored by Ko Yo-Han in the 72nd minute.
The result leaves the Wanderers and FC Seoul, the team they defeated in last season's semi-finals, level on five points, second and third respectively behind leaders Guangzhou Evergrande.
The Wanderers opened the scoring with the first attack of note from either team in the 12th minute.
Iacopo La Rocca's long forward pass was met by the head of left-back Kim Chi-Woo, who inadvertently nodded the ball directly into the path of Bulut.
On the day police charges against the striker - of intimidation at a fast food restaurant - were dropped, he celebrated by slotting a typically confident finish beyond the reach of goalkeeper Kim Yong-Dae.
After surviving an earlier injury scare, Labinot Haliti should have doubled the hosts' advantage in the 37th minute. Beating the offside trap, the unmarked forward stooped to meet Anthony Golec's cross from the left but could only send a tame header harmlessly wide.
The visitors began to threaten as the first half wore on, most notably in the 45th minute when Ante Covic was required to dash out of his goal and dispossess Yun Il-Lok with a sliding challenge almost 25 metres out of his area. The veteran keeper's timing had to be perfect, with a certain red card the alternative.
Seoul coach Choi Yong-Soo made two substitutions at the break and was rewarded with a strong start to the second half from his players.
The away team came agonisingly close to equalising in the 53rd minute, Colombian Mauricio Molina - impressive throughout but particularly so in the second period - unleashing a fierce shot which crashed into the underside of the crossbar and only bounced clear of the goal-line by a matter of inches.
The pressure continued to build and with 18 minutes to go, a chance arrived that the 2013 finalists couldn't miss.
Veteran right-back Cha Du-Ri played Everton Santos into space inside the area and the Brazilian's ball across the face of goal was slammed home at close range by substitute Ko.
A frantic climax to the contest saw both teams have strong penalty appeals dismissed, Tomi Juric hauled down by Cha before substitute Jason Trifiro appeared to handle inside the area from a Seoul corner.
In time added on Romeo Castelen had a shot saved when played in one-on-one with Kim, who also parried clear Trifiro's follow-up. At the other end Ante Covic then appeared to carry the ball across the line after making a save from looping volleyed effort.
As it was neither side could force the winner, leaving the two teams still scrapping to join likely group winners Guangzhou Evergrande in the knockout stages.
Next up in this competition for Tony Popovic's men is a home match with the group's bottom side Kashima Antlers on April 21, when Seoul play host to the leaders.
Western Sydney Wanderers 1 (Bulut 12’)
FC Seoul 1 (Go Yo Han 72’)