[citation needed] At only 12 years of age, Greenwood was contacted by Nottingham Forest and was asked to join them for a two-week trial period.

[citation needed] He joined the Manchester United under-13s side as a right-back and occasional centre-back and played in the same team as Chris Eagles and Phil Picken, as well as training with older players such as Kieran Richardson.

[citation needed] Assistant manager Mark Smith singled him out for praise for dealing with opponents who were recently in the Premier League.

[citation needed] After this impressive start, Greenwood only made two more substitute appearances before being deemed not good enough by new manager Paul Sturrock.

[citation needed] A move back to Yorkshire and his hometown came 17 July 2006 as he was signed by Conference National side York City.