Reece James is "sad to say goodbye" to Mason Mount following his old pal's decision to leave Chelsea for Manchester United. 

Mount, 24, joined United on a five-year deal earlier today, with the option of a further 12 months, after making the tough call to end his 18-year association with the Blues. 

And James, who rose through the ranks alongside the midfielder for both club and country, could not hide the pain of seeing him leave their boyhood side. 

Writing on Instagram, he said: "Ma brother man. Where do I start? 

"I’ve known you since six, we grew together and took similar paths in breaking into the first team. 

"Something that seemed virtually impossible. I'm proud to say I done it alongside you. 

"I've seen you as a little boy and watched you grow into the man and player you are today — you've done yourself and your family proud. 

"We've had some of the best days of our career together that'll stick with me forever. 

"It's sad to say goodbye. I wish you nothing but happiness, good health and the best of luck on your new adventure! 

"You'll always be blue at heart!"

Within minutes of James posting his heartfelt farewell, Mount thanked his former team-mate.

He replied: "My brother from day one, so many memories shared together. Thank you RJ."

After completing his switch to Old Trafford, Mount said: "It's never easy leaving the club where you grew up but United will provide an exciting new challenge for the next phase of my career. 

"Having competed against them, I know 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 the club has made big steps forward under Erik ten Hag. 

"Having met the manager and discussed his plans, I couldn't be more excited and am ready for the hard work expected here.

"I'm hugely ambitious. I know how amazing it feels to win major trophies and what it takes to do it. 

"I'll be giving everything to experience that again at United."