Graham Arnold was sticking posters on the wall.

'Greatest Socceroos Team In History' was the boldly printed message.

Arnold stuck the posters to the walls of change rooms in Turkey at his first training camp as Socceroos coach.

He plastered them around dressing rooms in Canberra before Australia's first home World Cup qualifier in October 2019.

The stated ambition was simple.

"That was my goals, my expectations and my dreams to do that," Arnold told reporters.

But even his players took some convincing it was possible.

"It takes you after a certain amount of time to realise he's right," defender Milos Degenek said.

"You have to buy into what he's doing. If you don't buy into it, you're not part of the squad. And all these boys bought into that.

"Arnie has got that mentality that has been passed on to us - that you have got to visualise it, you have got to dream it, you have got to speak it, believe it, and then it happens.

"He has really wanted it since day one, since his first training session we had in Turkey, he said he wants to be the coach of the greatest Socceroos team ever.

"Arnie has proven that he is one of the greatest coaches that Australia has ever had.

"And I think this generation has proven that it could be the greatest generation ever."

The evidence is compelling: Arnold has steered the Socceroos to the knockout stages of a World Cup for just the second time.

And they're the first Australian team to win two games, and keep two clean sheets, at a single cup.

Arnold's poster dream is reality.

"You probably can say that's what we've achieved too now," Arnold said.

"But we're not finished.

"I just want more for the players and the game, it's just my passion in my heart that I have for Australian football and these kids."

Arnold said his joy came from players such as 24-year-old Keanu Baccus shining on the world stage; to see his defensive pillar Harry Souttar do likewise; to witness his trusted stalwart Mathew Leckie score.

"And to see the experienced players, since I have been with them, grow as leaders," Arnold said.

"It just feels so different now because when I first took over, losing the leaders like (Tim) Cahill, (Mile) Jedinak and (Mark) Milligan.

"Having to recreate and build other leaders ... and helping young kids with their lives and fulfilling their dreams is more important than anything."