Zoran Tosic has explained just how demanding Manchester United training sessions were during his time at the club.

The Serb joined United in a £7million deal from Partizan Belgrade in January 2009, but failed to make an impact during his short time there.

Getty 3 Zoran Tosic spent just one year at Old Trafford

Tosic was just 21 years old and struggled to adapt to English football, making just five substitute appearances before permanently leaving for CSKA Moscow in the summer of 2010.

Now 32 and playing for Partizan Belgrade – United’s next opponents in the Europa League – he told the Athletic: “I was put straight into the first-team squad and the levels were so high that it felt like another sport.

“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.”

Tosic says he was shocked by the professionalism and quality from veteran players such as Ryan Giggs and Paul Scholes.

Getty 3 Tosic said he learned a lot from Ryan Giggs and Paul Scholes

He admitted ‘learning so much’ from the two Manchester United legends, who he said trained at ‘200 per cent.’

The former Serbia winger said: “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.

“They didn’t know it but I learned so much from copying them. There was a gym in Belgrade but nobody really used it.

“We do now, it’s normal in Serbian football, but when I first arrived in England I would go back to my hotel alone and say to myself, ‘come on, step up!’ But it would take time.”

Getty Images 3 Nemanja Vidic captained Manchester United for three years

Nemanja Vidic, who won five Premier League titles with Manchester United, believes compatriot Tosic could not cope with the physical demands of English football.

“Zoran, he was a good player – he is a good player – you don’t sign for Man United under [Sir Alex] Ferguson if you’re not a good player.

“But his problem when he arrived was that he was not ready physically. He’d come from the Serbian league and there’s a big difference between that and the Premier League.

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“Going to Russia first really helped me because Russia was tough, but Zoran didn’t have that.

“So he had to spend six months in a gym building himself up and he did really well, but we had a really top team.

“He was in competition with [Cristiano] Ronaldo, Nani and Giggs. It would have been difficult for any player in the world to get in the team ahead of them.”