Ange Postecoglou has sensationally quit as Australian coach just days after leading the team to their fourth consecutive World Cup.
An emotional Postecoglou delivered the news in a press conference alongside FFA CEO David Gallop on Wednesday morning.
"This has been a very tough decision for me," Postecoglou said.
"It has been a privilege for me to coach my country’s national team, to lead them at the 2014 World Cup, to win the Asian Cup in 2015 and now to have qualified for the World Cup next year. I said we would do it and we have done it.
"All this however, has taken a toll on me both personally and professionally. I have invested all I can knowing how important a period it was for Australian football. It is with a heavy heart that I must now end the journey."
Gallop expressed his confusion at Postecoglou's decision but thanked the 52-year-old for leaving a legacy since taking over the role from Holger Osieck ahead of the 2014 World Cup.
"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."
A successor for Postecoglou has yet to be announced but with the Socceroos' next match not until the international window in March, Gallop explained there will be no rush to appoint a new leader.
He also believes the fact Australia is in the World Cup makes the vacant role attractive to prospective managers.
"With a guaranteed place in the World Cup, I am sure we will attract a strong field of candidates," he said.
"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."
Australia qualified for Russia after a 3-1 second leg win at home against Honduras in the intercontinental playoff last week.