Diallo has signed a four-and-a-half-year contract, tying him to the Premier League giant until June 2025.

United's pursuit of Diallo began in 2016 and the 18-year-old has since broken through in Serie A, playing five first-team games and scoring once for Atalanta. 

A deal had been agreed in October and now a work permit has been secured that allows the move to take place. 

United said, in a statement on their website, that Diallo would join up with them as soon as he receives a visa.

Reports have indicated the transfer will cost United £37million, but Solskjaer believes they are getting a rare talent. 

Solskjaer said: "As a club, we have followed Amad for a number of years and having watched him myself, I believe he is one of the most exciting young prospects in the game. 

"Manchester United has such a proud history of developing young players and everything is in place to enable Amad to reach his potential here. 

"It will take time for him to adapt but his speed, vision and fantastic dribbling ability will stand him in good stead to make the transition. He is a player with all of the raw attributes that are needed to be an important player for Manchester United in the years to come." 

Diallo is relishing his big chance at United, saying: "After waiting since the summer, it is finally a dream come true to complete my move to Manchester United. I am hugely ambitious and there is so much that I want to achieve in the game; when I spoke to the manager I knew that I had joined the perfect club. 

"This is a really exciting squad with so many great players, I can promise that I will work hard every day to learn from them and give everything to develop my game. The coaches have been fantastic since I signed, we have been in touch regularly and they have already given me a lot of great advice. 

"I have had time to prepare for this move, both physically and mentally, and I have worked really hard to be ready to make the step up to this amazing club."