To cap the night, the 19,369-strong crowd stayed back to watch the Wanderers be presented with the Premiers Plate by FFA chief executive David Gallop.
But while the entire stadium erupted in jubilation when the final whistle was blown Popovic sat unmoved in his sideline chair.
"I'm not sure what was going through my head," he said later.
"Obviously I was pleased. But I just feel like there's still more to do next week.
"It's not daunting though at all.
"The Premiers Plate was different. When we won in Newcastle we knew we had won it and achieved something.
"But in this finals series we've achieved nothing yet.
"So come next Sunday we'll do everything we can to hold up another trophy."
The Roar were beaten in their previous three encounters with Western Sydney and, again, the supremely organised Wanderers were too strong in defence and too quick on the break.
Kresinger forced the first save of the match and only a minute later got past Roar gloveman Michael Theo to break the deadlock after 16 minutes.
Ono put the game beyond doubt in 72nd minute, displaying his supreme skill to catch the Roar 'keeper completely off guard with an audacious chip into the back of the net from outside the box.
Roar coach Mike Mulvey conceded that stopped any momentum his side were trying to gain.
Mitch Nichols and Ben Halloran threatened but Wanderers 'keeper Ante Covic was otherwise untroubled with his defence able to nullify superstriker Besart Berisha and skipper Thomas Broich's impact.
"What an outrageously brilliant goal by Ono. I mean that was the nail in the coffin for us," he said.
"We were just coming back into it and creating chances and he scores a goal like that. It was a moment of genius.
"I just want to congratulate Western Sydney. It's been a marvellous achievement.
"On reflection they were the better side over the whole 90 minutes tonight.
But it wasn't all good news for the Wanderers who will now be without key midfielder Youssouf Hersi for the grand final after he was sent off in the 78th minute with a second yellow card for a foul on Massimo Murdocca.
"It's hard to say I'm not disappointed," Popovic said.
"He's unpredictable and his intensity is high. He gives everything he has and it's all at 100 miles an hour.
"It was just that exuberance that has unfortunately cost him."
- AAP