The 32-year-old, who has been a major part of the recovery inspired by new boss Kevin Keegan in recent weeks, has been playing with an injury which it is understood could require surgery at the end of the campaign.
Socceroos coach Pim Verbeek said: "Nobody can do the same as Mark Viduka. I have seen enough games in England and Europe - he is special. You don´t see players like him very often. He is so important for the team he is playing at."
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