While Postecoglou's first act when he took over was to rejuvenate the squad, it was Cahill, the sole survivor of the cull of Australian's 'golden generation', who was among the first to offer his gratitude.
"The last four years have been amazing and he has helped create memories that will last forever for our country," Australia's leading international scorer with 50 goals said in an Instagram post.
"His leadership and beliefs are infectious and I'm proud that I had the chance to share his journey with him and witness his love for our country.
"The most important part was the belief he instilled in us to play a style of football that could test any team we came up against. This for me sets Ange apart as someone that stayed strong to his values of changing the game in Australia."
Postecoglou's determination to prove to the world that Australians could play decent football clearly rubbed off on his players.
"He completely changed my approach to life as a person and a footballer," said defender Bailey Wright, who added that he was "gutted" to see the coach resign.
"The foundations he has laid down for Australian football will forever be remembered when we look back at when our game changed for the better in our country."
Other players that Postecoglou brought into international football, such as midfielders Aaron Mooy and Massimo Luongo, took to social media to thank their former coach for believing in them.
"He gave me my shot with the national team and I can never forget that," added defender Trent Sainsbury.
"The belief and confidence he's instilled in this team that will keep us on the path to great things."
An emotional Postecoglou said in his resignation news conference on Wednesday that he had not told the players of his plans to step down because it would have been "too hard".
Football Federation Australia (FFA) said on Wednesday there would be no hurry to name a replacement coach but it was clear from the player tributes that Postecoglou had left behind a squad with a very strong sense of identity.
"His saying that will stay with me forever is 'NEVER TAKE A BACKWARDS STEP'," Cahill concluded.
(Editing by John O'Brien)
