Former Manchester United star Zoran Tosic has opened up about his Old Trafford failure.

The Partizan Belgrade star is set to face off against his old side.

Tosic joined United in 2009 under Sir Alex Ferguson and was hailed as a huge youth prospect at the time.

But his move did not pan out and he left the club after a year.

"I was put straight into the first-team squad and the levels were so high that it felt like another sport," Tosic told The Athletic.

"It was very heavy for me in those first weeks in Manchester. The ball moved so quickly in training, the quality was top, top, level. Nobody lost the ball. Except me. I was trying my best but it wasn't enough. This wasn't the football I knew.

"I thought I could play for United but there was a reason I was not at their level. These players lived the football life at the top. Giggs was 36, Scholes 34. They trained at 200 per cent. They lived football 24 hours. It was a big surprise to me to see them do this, a big lesson. They were on bikes before training and in the gym after."