In their maiden campaign in the Asian competition, the Wanderers have impressed and eliminated defending champions Guangzhou Evergrande in the last eight.
Goalkeeper Ante Covic said Tony Popovic's squad understood just how big an occasion it was.
"To play a semi-final of the Champions League, it doesn't get much bigger," he told the club's website before they left for Seoul.
"We're really looking forward to it, we've got a chance to go to the final and then go even further than that.
"There's so much dangling there in front of us to achieve and a moment that a lot of us are going to look back and think 'wow, that was a big game, a big moment' and we've just got to make sure it's not the last two games."
Choi Yong-soo's Seoul are in decent form ahead of the clash, unbeaten in 10 matches in all competitions.
However, the A-League side are without suspended striker Tomi Juric, who scored both of the Wanderers' goals in their shock quarter-final defeat of Evergrande.
