With Ange Postecoglou on the verge of making history in Japan, Australian soccer is wondering again what might have been.

Nearly two years after is shock resignation as Socceroos coach, Postecoglou has a big chance to add another stellar achievement to his footballing journey: a J-League title.

Early in his tenure at Yokohama F.Marinos, his side toyed with relegation, but ultimately finished 12th in the 18-team competition, along with making the Emperor's Cup final.

Now at the tail end of his second season, Postecoglou has his team one point off top spot in the competition with five games to play.

But beyond results, he has his side playing the attacking, enthralling brand of football that captivated Australia during his stint at Brisbane Roar, then with the Socceroos.

Ex-Melbourne Victory coach Kevin Muscat, who worked under Postecoglou, is unsurprised by his former mentor's success but laments the loss to Australian football.

Postecoglou quit the Socceroos after ensuring qualification for the 2018 World Cup, having come under increased pressure and scrutiny in the latter stages of the campaign.

"I couldn't be any happier for him," Muscat told AAP.

"Without getting caught up in the results ... the way he's going about it and the football they're playing fills me with a lot of joy because I've got similar love about the game that he does so I enjoy watching his teams play.

"On the flip side, I can't help but feel sad and disappointed that we didn't really give his vision enough respect and many, many people questioned; and eventually got what they wanted in him moving on.

"So I feel sad for the country that we didn't get to bear the fruit of his vision."

Neither does Postecoglou's success overseas come as a surprise to one of his most-respected former players, Matt McKay.

"He pretty much makes (players) buy in. And if they don't then they won't be there," McKay told AAP.

"So maybe there was a bit of turnover but he believes in the guys he has."

McKay was captain under Postecoglou during the 2010-11 season when the Roar went 28 games unbeaten - including winning the A-League Premiers Plate and the grand final. He was also part of the coach's 2015 Asian Cup-winning Socceroos side.

He compared the transformation at F.Marinos to Postecoglou's first season at the Roar, where he spent the closing months of 2009-10 refining a game plan that would hold them in good stead for their dominant season - a period that saw the team dubbed "Roarcelona".

"He was trying to mould his team for the next year and that was the year we won it," McKay said.

"We had a long pre-season but he was very distinct in how he wanted to play, so everyone knew their responsibility in a team.

"He had that well drilled into his players. I think that was pretty crucial that you knew what you had to do in certain situations and he planned sessions and talks around that.

"As a player you don't really learn that then, you see that in years after that - you can see how he actually planned sessions and made you do things that will ultimately help the team move forward."

McKay said he believed Postecoglou had grown as a coach over the years, from a more "standoff-ish" approach in his early days, to a "very good man manager" who was tactically and technically astute but continued to develop and learn along the way.

While Postecoglou enjoyed a superb club run in Australia, along with a fine stint as national team coach, McKay expected his former mentor to continue looking forward, rather than back.

"I think he's kind of outgrown Australia to be honest and I don't think Japan's the last step for him," McKay said.

"He's conquered Asia at international level with our Asian Cup and hopefully he wins the J.League title and then he gets over to Europe.

"I'm sure he's got ambitions to go over there and he's good enough to do it."