Chelsea have agreed a British record 121m euro (£107m) deal for Benfica's Argentina midfielder Enzo Fernandez.
Benfica said in a statement it had "reached an agreement with Chelsea FC for the sale of all the rights of the player Enzo Fernandez".
Fernandez, who only joined Benfica for a reported £10m in August, was named young player of the tournament during Argentina's World Cup triumph in Qatar.
The 22-year-old's arrival takes Chelsea's January spending to £288m, according to transfer website Transfermarkt.
That follows an outlay of around £270m in the summer - a record for a British club in the summer window - taking their total spend under new American owner Todd Boehly to more than £550m on 17 new players.