An elite team of 33 players is now in training on the New South Wales Central Coast in an attempt to secure spots in the Olyroos' final 18.
Three over-age players will be allowed in Australia's under-23 squad.
Olyroos assistant coach Ron Smith says many of the Socceroos have told him they are keen to play.
"Certainly Harry could well be in with a shout ... there has been a number (of interested players) but I won't mention any names," he said.
"A number of the senior players have said to (coach Graham Arnold) that look, you know, 'Consider me I'd be very interested', and I think that is a great sign.
"Graham has obviously spoken to one or two players to see of they are interested and so on and so far virtually everybody has said yes."