Speculation over Postecoglou's future has been rife throughout Spurs' run to Bilbao, with make-or-break ties against AZ Alkmaar, Eintracht Frankfurt and Bodo/Glimt navigated.
With Tottenham down in 17th in the Premier League, Postecoglou admitted last month the "general sentiment" was he would leave even if he ended the club's 17-year trophy drought, but during a fiery press conference at San Mames, the embattled head coach felt his work in north London was far from finished.
"I don't think my job is done here," Postecoglou said before Wednesday's showpiece with Manchester United.
"I really feel like we are building something and what a trophy does is hopefully accelerate that. So, I still think there is work to be done.
"It is quite obvious with the challenges we've had this year, which I think are well chronicled, but there is some reasoning in the context of that, but also there has been some growth I would like to see through.
"Whether that happens or not is not that important right now, but I don't think far from it is this job finished. I certainly feel there is some growth there that we can take this club to where it needs to be.
"I've been in this position before where the big game was the last game I managed. It's not unusual territory for me.
"I have always navigated it pretty well because for me, nothing is more important than my responsibility for this football club and its fans. Tomorrow me, the players, our mind is only on one thing and that is to create something special."
Spurs' domestic struggles mean Postecoglou has presided over the club's worst Premier League campaign with a record tally of 21 defeats, but he also stands on the brink of the holy grail - eagerly-awaited silverware.
Asked about the fine line between "infamy" and "legendary status", Postecoglou snapped: "I'll tell you one thing, irrespective of what happens tomorrow, I'm not a clown and I never will be.
"I'm really disappointed that you would use such terminology about a person who for 26 years without any favours from anyone has worked his way to a position where he's leading out a club in a European major competition (final)."