However, Mainoo will now have to tough it out after he was told he would not be allowed to leave before the summer transfer window shut on Monday at 19:00 BST for Premier League and English Football League (EFL) clubs.
DID YOU KNOW?
Speaking after United's 1-1 draw with Fulham on August 24, Amorim explained that Mainoo is actually competing with captain Bruno Fernandes for the same place in his starting eleven, with the Portuguese seemingly unenthusiastic about playing the midfield pair together.
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WHAT NEXT FOR MAINOO AND MAN UTD?
Mainoo will be hoping to make an appearance when United take on rivals Manchester City in the derby on September 14, following the conclusion of the international break. Amorim's men then take on Chelsea at Old Trafford on September 20.