The 20-year-old footballer has been placed in custody after a woman accused him of rape and assault in a social media post on Sunday.
According to Sky News, the now deleted social media posts included video, photographs, and a voice note alleged to be a conversation between Greenwood and the woman.
The Greater Manchester Police said: ‘An investigation was launched and following inquiries we can confirm a man in his 20s has since been arrested on suspicion of rape and assault.
‘He remains in custody for questioning.’
Manchester United said in a statement that the club was ‘aware of images and allegations circulating on social media’ but declined to comment further until all the facts had been established.
The club confirmed that Greenwood would not be returning to training or matches until further notice, adding that they ‘do not condone violence of any kind’.
Nike, Greenwood’s sponsor, said it was ‘deeply concerned’ by the allegations and will continue to monitor the situation.
Greenwood has yet to respond to the social media allegations.