Belgrade, 16 November 2007. Their Royal Highnesses Crown Prince Alexander II and Crown Princess Katherine attended last night 20th birthday party in honour of Ana Ivanovic, one of the most successful tennis stars in the World today.
The big birthday party was held at the Zira Shopping Centre and it lasted late into the night, gathering numerous prominent personalities and officials, among others were: HE Mr. Boris Tadic, President of Serbia, Mr. Miroslav Miskovic, President of Delta Company, Mr. Vlade Divac (NBA Star), Zarko Paspalj, Dragan Dzajic (Red Star football legend) ... Boban Tanovic of EtonDigital and many others.
More photos on Ana's Official website

correction to your post:
Alexander II and his wife are not the monarchs of the REPUBLIC of Serbija.
Here’s proof: http://www.srbija.sr.gov.yu/pages/intro.php?id=5
The Karadjordje family are surviving off of a Republic of Serbi heritage budget because they live in historical heritage builings (palace).
He may not be your King bet he is mine!!!!