Chelsea have signed Borussia Dortmund forward Christian Pulisic for 64m euros, but will loan him back to the German club until the end of the season.

The 20-year-old United States international, who was linked with Liverpool and Arsenal, joined Dortmund as a youth player in 2015.

Pulisic has scored nine goals in 23 games for the US.

This is the highest transfer fee for an American player, beating the 20m euros Wolfsburg paid for John Brooks in 2017.