Adem Ljajic will miss Partizan Belgrade's UEFA Champions League qualifier with Rhyl to rest ahead of the European Under 19 Championship.
The 17-year-old signed for Manchester United last January alongside fellow Partizan team-mate Zoran Tosic but was immediately loaned back to the Serbian club.
The midfielder, who is held in high regard at Old Trafford, will return to the Premier League champions for the start of 2010.
Partizan manager Slavisa Jokanovic has excused the Serbian youngster from travelling to Wales for the first-leg of the second qualifying round of the Champions League tie.
Despite authorising Ljajic to miss the clash, which Partizan are overwhelming favourites for, Jokanovic insists he is not taking the game lightly.
"I approach each game in a serious way," he said. "We have no right to underestimate any club, any country.
"We have all played matches against semi-professional sides and no-one is going to give you anything."
The Under 19 European Championship begin on July 21st and will be staged in the Ukraine.