Graham Arnold has revealed he received dozens of knock backs from overseas clubs as he tried to get players made available for Australia's Olympic football campaign.

The 18-man Olyroos squad for Australia's first men's football appearance at the Games since 2008 was revealed on Tuesday with just two of three possible over-age players named by Arnold.

Striker Mitchell Duke and defender Ruon Tongyik are the two players over 23 that Arnold named, with stars such as Mathew Leckie, Jackson Irvine, Tom Rogic, Aaron Mooy and Mat Ryan absent.

Arnold said FIFA regulations allowing clubs to make players unavailable for selection had worked against him.

"This is probably one of the most complicated processes I've ever been through to select the squad," Arnold said.

"I probably made 30 to 40 phone calls to clubs for over-age players to see which players could get released. Pretty much out of 30-40, came back three (positive)."

As well as clubs refusing to release players, several ruled themselves out for a variety of personal reasons.

Mooy's absence is understandable given the recent death of his brother Alex while Arnold said members of the recent Socceroos squad such as Jamie Maclaren and Rhyan Grant have been given a break.

"We looked at that as Socceroos is priority number one for the third phase (of World Cup qualifying)," Arnold said.

"I always stated and, I mean this, that I wasn't going to build a squad around three over-age players, it's more about filling spaces, if we need."

Arnold isn't the only Olympic coach facing unavailability of leading players.

Australia's group rivals Spain will pick from outside their Euros squad with Arsenal's Dani Ceballos and Real Madrid's Marco Asensio expected to be their key over-age talent.

Fellow group opponents Argentina will also be limited given their country's current commitments in the Copa America.

Along with Duke and Tongyik, the squad includes current Socceroos Harry Souttar, Denis Genreau and Connor Metcalfe.

Souttar, the Scottish-born defender who has scored six goals in five international appearances for Australia, was given permission to play by English championship club Stoke, drawing praise from Arnold.

"They want what's best for Harry, the player, they know how much Harry wants to play for Australia," he said.

"He's a kid that bangs on the manager's door and says 'I want to do this and I want to go to the Olympics' and makes it clear that it'd be better for him in the long run, and Stoke City."

Winger Daniel Arzani has been named despite his horror 18 months which has included serious injury and limited game time at three different European clubs.

There's also spots for Nathaniel Atkinson - who won the Joe Marston Medal in Melbourne City's A-League grand final win on Sunday - and Riley McGree.

The duo, along with Brandon Wilson and Lachlan Wales, were handed lengthy bans in late 2019 for an off-field incident in Cambodia while on Olyroos duty, missing the 2020 Asian under-23 championships where Australia booked their ticket to Tokyo.

"Everyone makes mistakes in life and they got punished for it," Arnold said.

"Yes, I was extremely disappointed in the behaviour but ... I don't hold grudges, they have thoroughly earned their position in this squad."

Australia's tournament begins on July 22 against Argentina, with Egypt the other team they'll face in Group C.

OLYROOS SQUAD: Daniel Arzani, Nathaniel Atkinson, Keanu Baccus, Nicholas D'Agostino, Thomas Deng, Mitchell Duke, Denis Genreau, Thomas Glover, Joel King, Ashley Maynard-Brewer, Riley McGree, Connor Metcalfe, Dylan Pierias, Reno Piscopo, Kye Rowles, Harry Souttar, Ruon Tongyik, Caleb Watts.