On his own website Novak Djokovic spells his name Dokovic. Why then does the media insert the letter J? Could it be the same reason they pronounce all foreign Davids as Davvid and the Dutch Football team Ajax as EYE-Yacks when it has recently emerged as being pronounced in the same way as the cleaning material AJAX? Also when Frank LeBoeuf joined Chelsea, they repeatedly referred to him as Franck LeBoeuf which annoyed him intensely.
The Serbians use the Cyrillic alphabet so the only correct spelling is in that alphabet . Transliterating into the latin (western) alphabet , any spelling which leads to the correct pronunciation will do - e.g. - the German transliteration would replace the "v" with a "w" .