Known as 'Little Kaka' in his home country for his dribbling ability, Ljajic recently broke into Partizan Belgrade's senior side for their Champions League qualifiers.
United were previously linked with Partizan's 18-year-old striker Stevan Jovetic, who transferred to Fiorentina in the summer for £6million.
Ljajic played for Serbia's Under-19s in their 3-1 win over Northern Ireland in Belfast last week and came over to Manchester following that match.
Scouts in the crowd at Seaview that night saw teenage United keeper Conor Devlin have a poor game, but will have taken note of Serbia's best player on the night - playmaker Danijel Aleksic - who is also being tracked at Old Trafford.




