Australia's new leading man believes Muscat is the right man to take control at Melbourne Victory
Fresh from his official unveiling as the new Socceroos boss in Sydney on Tuesday, Postecoglou threw his support behind former Victory captain and current assistant Muscat to take over the first-team duties at AAMI Park.
"I think he's an outstanding candidate to take over the job," Postecoglou said on Thursday.
"He's done his apprenticeship and worked very, very hard these last 18 months and he's been a big part of what's happened in these last 18 months.
"I've thrown a lot of responsibility on him, but he's welcomed that.
"We've spoken a lot about young players these last few days and regeneration – it's no different with coaches. At some point you've got to throw them in there, and I've got no doubt if Kevin gets the opportunity I've got no doubt he'll do a great job."
Postecoglou refuted the suggestion his side would be any more motivated to win his final A-League game in charge - co-incidentally against the club he steered to two championship titles Brisbane Roar at Etihad Stadium on Friday night.
"Do it for me? Nah I'm not big into that, it's a big enough game as it is," he said.
"As I keep saying (and) it's what this club's about - every week we seem to have a big game, first game was a massive game and this game is a massive game.
"There's plenty of motivators there without having to add any extra to it."
Postecoglou said he was disappointed not to have taken Victory to the same heights as he did Brisbane, but had full confidence the off- and on-field teams he had set-up over the past 18 months were capable of carrying on without him.
"No doubt," Postecoglou said, when asked if he was disappointed not to finish what he started at Victory.
"It's been a tough two weeks for me personally and for my family, and everyone around me because we've loved being at this football club. We've been really embrace by everybody, as a coach you never know when your end date is. It's rarely by your own choosing.
"I think everyone agrees the timing is terrible, but at the same time the opportunity to coach a national team for me is a once-in-a lifetime opportunity, and one I couldn't turn down.
"I really still firmly believe the job will be finished (at Victory) - this was never built as a one-man show."
On the expected reaction from Victory fans, Postecoglou understood not all would be happy about the move - but he said either way, the supporters were behind the club as they prepared for yet another coaching transition.
"The one thing I know about Melbourne Victory supporters is that they are passionate about their football club.
"They're going to want us to win.
"Post the game, there may be mixed emotions amongst the fans as well but no-one can deny they're very passionate about their football club."