The Wanderers rescued their floundering continental foray in the nick of time on Wednesday night, edging the K-League giants 3-2 in Korea despite nearly blowing a three-goal lead.
The assured performance breathed life into an A-League outfit smarting from a horrid few weeks at home and abroad, where 4-0 and 5-1 ACL annihilations to Urawa Red Diamonds and Shanghai SIPG left them on the brink of an early exit.
It also restored some patriotic pride as the first win for an Australian club in the 2017 tournament.
Brisbane's hopes of progressing from Group E appear marginal after Tuesday's 3-0 defeat to Kashima Antlers in Japan, while Adelaide's high-octane 3-3 draw with Jeju United on Wednesday keeps them within touching distance of Group H's top two.
The third-placed Wanderers (three points) are the only A-League team no longer last at the group-stage midpoint, though results must fall their way to catch Group F leaders SIPG (nine points) and Urawa (six points).
Popovic said the victory had injected much-needed belief that his squad would take to Campbelltown Stadium against Seoul on April 11.
"We will gain a lot of confidence from this performance and result," Popovic said.
"Now we want to repeat this at our home ground.
"If we can all be fit and healthy I believe we give ourselves a very good opportunity to get another three points against FC Seoul."
Before then come the pivotal final four A-League rounds, set to determine whether the Wanderers can hold onto sixth spot.
The race to the finals restarts at Spotless Stadium on Sunday against seventh-placed Wellington, who sit just two points behind, while Newcastle are one point further adrift.
Teenage striker Lachlan Scott will likely get a rest after scoring against Seoul on his ACL debut, before provider Terry Antonis buried a penalty and Jaushua Sotirio added a third.
Though Yun Il-Lok bagged a second-half brace the Wanderers looked comfortable throughout, something Popovic put partly down to the A-League's split round.
"They played on the weekend, we didn't," he said.
"We had 10 days' preparation so I felt we looked fresher and maybe sharper than them, which you would expect.
"We made the most of this and scored when we had our opportunities.
"That was the key for us, that we utilised physically the strength that we had."