Christian Pulisic says he is excited by the challenge of playing for Chelsea in the Premier League, but will give his all for Borussia Dortmund before he leaves in the summer.
The USA international joined Chelsea in a £57.6m move on Wednesday but was immediately loaned back to the Bundesliga leaders until the end of the season.
Pulisic will now aim to bow out in style by trying to secure some silverware with Dortmund, who are six points clear of Bayern Munich at the top of the German league table during the winter break.
"It's good now that it's out and people know about my future but I'm really excited I have the chance to be here for the rest of the season," the 20-year-old said at Dortmund's training camp in Marbella.
"The only thing I can say is I hope people understand my decision and I also hope they understand that I am here 100 per cent and very focused to finish out the season with Dortmund. I am really excited.
"It's a really good time for me and I have had an amazing five years in Germany. It's been incredible and I am so thankful for that.
"It's been a dream of mine [to play in the Premier League] and I am really excited for this move and I feel like it was just the right time for me."
Pulisic becomes the second most expensive outfield player in Chelsea's history, after striker Alvaro Morata.
"I've seen their style of play," he added.
"I've always appreciated how they've played football, and it's really nice how they play now, with their new coach. It fits me very well."