Sydney FC midfielder Terry Antonis and Germany-based forward Kwame Yeboah have been ruled out of the Olyroos squad which begins its bid to qualify for the Rio Olympics this week.
The injured pair have been replaced by teenage Sydney FC striker George Blackwood and Western Sydney Wanderers striker Jaushua Sotorio for the Asian Football Confederation (AFC) U-23 championship qualifiers in Taiwan starting on Friday.
The Olyroos face Hong Kong, Myanmar and host Taiwan as they attempt to earn a spot at the AFC U-23 Championship in Qatar in 2016.
That tournament also doubles as the qualification tournament for the 2016 Olympics with the top three teams advancing to Rio.
Antonis was sidelined from Sydney's 1-0 loss to Melbourne City on Friday and coach Graham Arnold said the 21-year-old had been struggling with a knee injury since his return after being part of the Socceroos' triumphant AFC Asian Cup 2015 squad in January.
FFA rules state if a player is ruled out of national duty with injury they cannot play for their club while the national team is away.
Arnold will also be without marquee striker Marc Janko for Sunday's crucial away clash with frontrunner Wellington Phoenix, with the big Austria striker away on national duty.