Milligan is captain of the Victory team that is challenging for the A-League title and was a member of the Socceroos side that won the AFC Asian Cup in January.
He has 'established' himself in the national team after making his debut in 2006 and he is expected to play for the green and gold in next week's glamorous international match against world champion Germany in Kaiserslautern.
The 29-year-old Sydneysider, however, believes that there is no such thing as an established Socceroos player.
Not while coach Ange Postecoglou is in charge, anyway.
"No, I don't think I've established myself in the team," Milligan said, as he prepared for the weekend A-League Round 22 match against fellow title aspirant Adelaide United at Coopers Stadium.
"I don't think the culture of the team now allows anybody to feel they have established themselves as a Socceroo.
"I reckon everybody understands that they have to earn a spot in the side every time games or tournaments come around.
"It's the modern way and Ange's way ... a little bit of both.
"Ange likes it this way. Playing in a Socceroos shirt should continuously have to be earned.
"Not that it was not like this before, I just think it has been shown now that no matter who you are or where you play ... if Ange thinks you can do a job for the team he is not afraid to use that player, no matter what league or country he plays in."
Milligan said the most pleasing aspect of the 2015 Asian Cup, apart from Australia's triumph, was the rapid rise of the national team - after losing its three matches at the 2014 FIFA World Cup.
"The fact that we have continued to grow from the very first day Ange came in is a big positive," he said.
"We had some tough results in the lead-up to the Asian Cup but nobody ever turned away from the way we were trying to play or what we where trying to achieve.
"Every player played a part in preparing for the cup and every player played his role in the final result."
Milligan is so convinced of the strength of the national team that he believes it has yet to reach its full potential.
"Its best is yet to come, most definitely," he said.
"There are still a lot of areas we can improve on. That was the catalyst of the Asian Cup and that will be what we will strive for going forward."
Before he jets out to Germany, Milligan will lead Victory in its key clash with the Reds on Saturday.
Victory is two points behind leader Wellington Phoenix but has a game in hand - against Brisbane Roar - so sole leadership beckons.
"We need to come out and get a good result this weekend," he said.
"It will be a tough match against Adelaide away from home but if we want to be contenders for the premiership we need to win this one.
"I think we still have work to do but we are building towards the finals."
Victory coach Kevin Muscat praised chief striker Besart Berisha after the impressive 3-0 win over Western Sydney Wanderers at the weekend.
The coach said Berisha brought much more to the team than just goals and Milligan was only too happy to expand.
"His work rate is second to none," Milligan explained.
"He doesn't give the opposing defence a moment's rest. He allows the boys behind to set up and he draws a lot of attention around the box even if he does not have the ball.
"Bes is also a winner and he motivates everybody around him to follow that lead."
