First of all, as a fellow Serbian I am SO PROUD to have my fellow countryman play for my favorite foreign club. And also it is a special bonus that he came from the youth academy of my favorite domestic club, Partizan.
Our most reputable football news site, MozzartSport, have also reported that the deal is closed and it will be announced very likely even tomorrow. And they rely on the sources close to the Dusan's agents (which they indeed have as they have reported earlier that he rejected the contract with Fiorentina even before it was out in the Italian press).
Also, I remember one interview from a few years ago when he was moved to Partizan's first team and they asked him for which team he would like to play in the future and he said without hesitation - Juventus. Oh, and also for those who don't know, Partizan and Juve share the same colors
Forza Dusan!