The keeper was born in Australia but has Croatian parents, although he had looked likely to represent the country of his birth.
He now seems to have had a change of heart and has angered Australians by saying that he will probably opt to turn out for Croatia should he be asked by coach Otto Baric.
"I think I have a better chance to play for Croatia," said Didulica.
"With Croatia I would get more chance to play at a high level at qualifications, and then there is the World Cup and European Championships.
"You can't travel all over the world just to play one game in two or three months. This is very hard and very exhausting."
Didulica has enjoyed a quick rise to the Ajax first team, and is amazed that two countries are now battling to get him in their squad, saying it is a very tough decision to make.
"This is sure one of the hardest decisions in my life, maybe for now I will concentrate on playing for Ajax and take time to decide.
"A few months ago I was still in the Ajax B team and now there are two countries fighting for me.
"If I agree to play for Australia I will have to wait as Mark Schwarzer is the number one goalie.
"If I go to Croatia, I will also have to wait because of Stipe Pletikosa but he is only with Hadjuk Split and I play for a big club in Ajax, so I believe it would be easier for me to get a chance.
"Yes, I have an Australian passport but, to be honest, deep inside I feel Croat so I will decide by listening to my heart."
