This is interesting b/c I've always noticed that many "immigrant" sports figures in Australia are more often than not have a strong emotional linkage with their parent's country of birth/background. And it's not just the sportsmen, it's many other "non-Australian" people as well. For example, back in high school, many of the Italians would proudly declare their Italian heritage and during the World Cup, it was all cheers for the Italians and jeers for Australia's failure to qualify.
My point is that I reckon Jelena will represent Australia for the sole purpose of her tennis career. But whether she thinks of herself as an "Aussie" is open to debate (I have a feeling that Jelena sees herself as a Serbian).