Mauricio Pochettino already has a fresh injury headache at Manchester United - and he's not even through the door yet. 

Patrick Dorgu has been sent home from Denmark duty having failed a series of physical tests. 

The full-back missed four Premier League matches in October due to a hamstring injury but came on to provide an assist and score the equaliser in the 4-4 draw with Aston Villa on Sunday.

Now he re-joins an injury list which includes Marcus Rashford, Luke Shaw, Carlos Baleba, and potentially Harry Maguire, with Manuel Ugarte and Benjamin Sesko ruled out longer-term. 

Denmark's team doctor Martin Boesen said: 'We have carried out a series of tests on Dorgu, and he has not performed well enough to be ready to play in the two matches. 

'He needs further recovery time after his injury, so we are sending him home for additional rehabilitation.'

Dorgu, 22, will miss matches against Portugal and Norway in the Nations League. 

Pochettino will hope Dorgu makes a quick recovery as he seeks to get Manchester United back on track.

United, who sit 18th in the Premier League, agreed to pay more than £10million to prise Pochettino and his staff away from the United States national team.

Pochettino has signed a two-and-a-half-year deal to replace Michael Carrick and will get down to business after his final matches in charge of the USA against Haiti on Saturday and Wednesday.

The former Southampton, Tottenham, and Chelsea boss broke down in tears as he began his farewell and admitted that he couldn’t turn down the ‘dream’ job of Manchester United head coach. 

Flanked by US Soccer Federation bosses at the team’s headquarters in Georgia, an emotional Pochettino wiped away tears as he thanked the players and staff.

‘I haven't prepared a speech, I'm talking with my heart,’ he said. ‘It's difficult for me to talk now because I am a very emotional guy.

‘When these moments arrive, it is always tough. Normally it is the opposite – you have been sacked! You cry because you want to stay.

‘I think it was one of the most difficult decisions of our career, but you have to move forward.  

‘Not too many opportunities can happen in your career with a side like Manchester United. That is difficult to turn down when it arrives.

‘In some part it’s a very sad decision, in another part we are professional and we are trying to make our dreams come true. We are excited for that step forward.'

The 54-year-old Argentine revealed that United first made contact on Sunday after the 4-4 draw in Carrick’s final game left the club in the relegation zone.

‘I never said I wanted to go back in the Premier League,’ said Pochettino, whose first game in charge of United will be against Liverpool at Anfield a week on Sunday. 

‘All of this was so quick because we arrived here last Friday and on Sunday afternoon this type of situation started to appear. There was some contact. When things became bigger, they are very sensitive.

‘We were very transparent with the federation and they understand the situation. The decision between US Soccer and Man United to agree to continue for these two games will not change our commitment.

‘That decision was between the three parties but, of course if Man United agreed different terms, I need to respect that.’