Nemanja Matic is a Manchester United player and Chelsea is set to receive around £50m for the Serbian midfielder, according to reports.
Matic has signed a three-year deal with the option of an extra year.
The 28 year old made 30 starts in Antonio Conte's first season at Stamford Bridge, with Cesc Fabregas largely playing second fiddle to the Serbian as the club's central midfielders vied for a spot alongside N'Golo Kante.
Manchester United manager, Jose Mourinho, who also also signed him into Chelsea was delighted with the signing and stated that Matic was always has player.
"Nemanja is a Manchester United player and a Jose Mourinho player" The self styled special said in a statement.
He represents everything we want in a footballer; loyalty, consistency, ambition, team player".
"I would like to thank him for his desire to join us because without that, it would be impossible to have him here. I am sure our players and supporters will love him".
Matic would be the 2nd key player to leave Chelsea after Diego Costa was told to seek his playing future elsewhere.
For Manchester United's part, Mourinho will be reunited with a player whom he requested during his previous spell at Chelsea, and will look to Matic to provide depth in a squad that he feels is still not complete.
A big welcome to Manchester united new number 31.
By Emmanuel Ndibe
Edited by Cosmos Chukwuemeka