Manchester United have completed the signing of Mason Mount from Chelsea for an initial £55m.
The overall fee for England international midfielder Mount could rise to £60m depending on success and appearances over several seasons.
The 24-year-old has signed a five-year deal at Old Trafford that runs until the summer of 2028 and has the option to be extended by a further year.
Mount becomes United's first summer signing and the transfer brings his 18-year association with Chelsea, during which he won the Champions League, UEFA Super Cup, and FIFA Club World Cup, to an end.
Mount, who will wear United's iconic No 7 shirt, 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."
Manchester United football director John Murtough said: "Mason is an extremely intelligent footballer and has so many fantastic technical qualities that will significantly add to our squad.
"We have admired his talents for a long time, so we are delighted that he has chosen to take the next steps in his career here at Old Trafford.
"His style of play and attributes are a perfect fit for this squad, and we all believe that he will only improve further working with Erik ten Hag and his coaching staff.
"Mason himself is a world-class player but he also has the ability to improve the players around him through his game intelligence and tactical awareness. We were particularly impressed by his strong desire to join United, and his thirst for further success, as we push to drive up our performance levels next season and beyond."
