USA international Christian Pulisic has expressed his excitement at joining Chelsea from Borussia Dortmund, calling the Blues a "legendary club".
The 20-year-old has moved to Stamford Bridge in a deal worth in a deal worth £58 million (€64m/$73m) but will be loaned back to Dortmund for the rest of the season.
In an emotional letter posted on social media, Pulisic praised his new employers but also paid tribute to Dortmund for the impact the club has had on his career.
"It is with a heavy heart that I announce that I will be entering my final months at (y)our world-famous club," he wrote on Twitter.
"It feels like only yesterday that I arrived in Dortmund as a raw, excited, very nervous but exceptionally proud 16-year-old from a small American town called Hershey. I had no idea what lay ahead but I soon discovered that as a young Schwarzgelben, I would be in the best possible hands.
"I would not be where I am today without the club and their believe in giving young players a chance. It's been an honor and a dream to pull on the black-and-yellow in front of the Sudtribune!
"Many, many memorable moments stand out - to have experienced all of them before my 20th birthday still feels, at times, like a dream. I would like to thank all those coaches who I have played under and who gave me these opportunities.
"And to my amazing teammates throughout the years: You took me in as a young boy, shared your experience with me, helped me to develop and grown into a professional footballer. For this I sincerely thank you.
"To our unbelievable fans: It's been a privilege to stand with you on the Sudtribune and to experience how you support your heroes. I feel honored to have been able to make the trip from being a supporter, to being supported. You have taken me in as one of your own. Thank you.
"I would also like to thank Mr. Watzke and Mr Zorc. It was very important to me that I handled my situation in as fair and professional manner as possible towards the club. So I thank them for finding a solution that was a win-win for everyone.
"In summer of 2019, I move on to Chelsea and to and to a new competition, the English Premier League. It's a privilege to have signed for such a legendary club and I look forward to working hard towards being a contributor to their team of world class players. Looking forward to working with Maurizio Sarri and his technical team.
"But for the next six months, it's all BVB! Please do not doubt my passion, determination and my 100% commitment to the team right until the last ball is kicked this season. We all feel that this is 'our year' and we are determined to achieve the best possible results in a ll competitions.