Mason Mount handed the iconic shirt after becoming their first signing of the summer.
Mason Mount will take the No 7 at Manchester United. He wore the shirt for Chelsea youth teams.
Ten Hag key in selling the club's vision and project to the midfielder and outlining the important role he'll play
The midfielder has penned a five-year contract on £250,000-a-week, keeping him at Old Trafford until 2028, with the option of a further year.
United will pay £55m plus a possible £5m in add-ons for the Englishman, who they believe is now entering his prime years at the age of 24.
Mail Sport sources say that Mount fits the mould of a dynamic energy player wanted by maanger Erik ten Hag, who was heavily involved in the process of the transfer. The Dutchman has already given Mount a clear vision of how he will fit into the team next season.
Mount wore the No 19 shirt while at Chelsea, where he was crowned Player of the Year for both the 2020-21 and 2021-22 seasons, also helping them to a famous Champions League victory in 2021.
After signing the deal with his new club, Mount said: 'It's never easy leaving the club where you grew up, but Manchester United will provide an exciting new challenge for the next phase of my career.
'Having competed against them, I know just how strong a squad it is that I'm joining, and I can't wait to be part of this group's drive to win major trophies.
'Everyone can see that the club has made big steps forward under Erik ten Hag. Having met with the manager and discussed his plans, I couldn't be more excited for the seasons ahead, and am ready for the hard work expected here.
'I am hugely ambitious; I know how amazing it feels to win major trophies and what it takes to do it. I will be giving everything to experience that again at Manchester United.'