Australia could be missing as many as three of their first-choice players for their friendly against Denmark in Copenhagen on Saturday.
Josh Kennedy and Carl Valeri will definitely sit out the clash due to club commitments while Aston Villa's Brett Holman is a doubt with his wife expecting to give birth to their second child.
Kennedy will play for Japanese outfit Nagoya Grampus in their round-of-16 AFC Champions League clash with Adelaide United at Hindmarsh Stadium on Tuesday, while Valeri will line up for US Sassuolo Calcio in their crucial Serie B promotion play-off matches against Sampdoria on Wednesday and Saturday.
However, Kennedy and Valeri will both rejoin the Socceroos squad for their World Cup qualifiers against Oman in Muscat on June 8 and Japan in Brisbane four days later.
But it is unclear whether Holman will be available for the match with the Omanis.
Meanwhile, reserve goalkeeper Adam Federici has pulled out of the squad for the matches with Denmark, Oman and Japan due to injury and has been replaced by Borussia Dortmund shot-stopper Mitchell Langerak.
Holman's Villa teammate Chris Herd has also been ruled out due to injury and does not have a replacement.
Australia squad for games against Denmark, Oman and Japan.