The 52-year-old announced on Wednesday that he was standing down as national team coach, a week after ensuring Australia would qualify for a fourth successive World Cup with a 3-1 victory over Honduras.

It comes after weeks of intense speculation over Postecoglou's future reached a crescendo with a crunch meeting with Football Federation Australia chief executive David Gallop and chairman Steven Lowy on Tuesday.

"A tough morning for me and probably 'DG' [FFA CEO David Gallop] as well, a tough 24 hours," Postecoglou said.

"The journey for me ends as Socceroos coach."

Postecoglou said it was not the ending he had envisaged when he started but he knew it was the right time and the right decision.

"It's something I've mulled over for a while, it's just the nature of me as a person. I've really tried to coach for the moment ... I think I'll always have a sense of unfinished business but to be honest that would have happened whenever I left.

"But overall, sometimes it's just an instinct, it's the right time for me, it's the right time for the team, the organisation ... for me it feels like the right time.

"To the players, I love coaching Australian players. I've often said to them when you make a choice in this country to play football ... you're choosing the hardest possible road and that takes courage, and that's why I love coaching Australian players.

"It's been the greatest privilege to me to coach our best players and I'll be forever indebted to them."

Gallop said he was disappointed Postecoglou would not be going with the Socceroos to Russia but thanked him and said he had given Socceroos fans "a sense of optimism".

"I'm disappointed and still a bit puzzled but still supportive that you reach a point where you know you need to do something new," Gallop said.

"Ange's record speaks for itself.

"It's important that we get the right person to fill the big shoes. One thing I do know that the standards that Ange set ... will now always be there and that's a huge part of the legacy that Ange leaves for the boys and the staff."

The Socceroos do not play again until March next year at the earliest and Gallop said that gave the FFA time to conduct a thorough process.

"With a guaranteed place in the World Cup, I am sure we will attract a strong field of candidates.

"There's enormous advantages to have an Australian in this position ... but it doesn't necessarily guarantee that we will be able to appoint an Australian. So we will take our time and make sure we get the right person for the job."

FFA chairman Steven Lowy said he respected Postecoglou's reasons for leaving.

"Like all Socceroos fans, we hoped Ange would stay on to the World Cup and maybe beyond. He has done an outstanding job and has always had our total support," Lowy said. "We wish him well for the future."

Postecoglou was visibly emotional when thanking his family for their support.

"To my three boys, James, Max, Alexi, you make me smile every day and to my beautiful wife ... I left 24 hours after Max was born because we played Ecuador in London ... I'll never be able to repay the sacrifices she's made.

"It's been the toughest decision ... but it won't take way how rich this experience has truly been.

"Bigger things were driving me when I took this job and from that perspective I've accomplished what I wanted to do."

With Australia having qualified for three consecutive World Cups, Postecoglou said he didn't want to be the coach who failed to qualify for the fourth and he had felt the weight of that responsibility over the past six months, leading him to ponder his future.

Postecoglou said he was keen to get back to club soccer and "working day-to-day".

"I loved this job but it has been all encompassing. I don't want to be unemployed for too long but I probably need to have a break with the family and regather my thoughts," he said,

Postecoglou, appearing on the ABC's Offsiders program on Sunday, implied that the month-long saga over his future had in part been dragged out so that he could be a shield for his players and take the pressure off them as pressure mounted during the World Cup play-offs.

"[My mindset] fluctuates all the time. I can't say that I am locked to a position," he said at the time.

Postecoglou was contracted until the end of the World Cup.

POSTECOGLOU'S TIME IN CHARGE

First match: November 19, 2013 v Costa Rica (Sydney)
Last match: November 15, 2017 v Honduras (Sydney)
Total number of matches: 49
Wins: 22
Draws: 12
Losses: 15

Fairfax Media with AAP