His new club - who he joined at the end of last season - revealed today he is set to go under the knife for a niggling groin injury.

Zadkovich had been tipped to take his Championship bow alongside Socceroo team-mate Mile Sterjovski as soon as this week.

The 22 year old scored the only goal of Australia's dismal Olympics campaign, netting in the opening match against Serbia.

But the club says the rigours of his international call-ups - playing for the Olyroos at the Olympics plus all the warm-up friendlies as well as his Socceroo cap against China in the World Cup qualifiers - have taken their toll.

"Ruben has been playing non-stop now for quite a while and has aggravated the problem. He is to see a specialist and could well need a little bit of surgery," Rams boss Paul Jewell told Derby's Evening Telegraph.