Chelsea have secured the services of Cristian Cuevas from Chilean Primera Division outfit O'Higgins.
Cuevas, who featured in Chile's FIFA Under-20 World Cup squad, has signed a contract with the club until 2018 and can operate on the left side of defence or midfield.
Jose Mourinho's latest recruit played in four of Chile's five games at the tournament in Turkey as they reached the quarter-finals before bowing out to Ghana.
A statement on the Premier League side's website read: "Chelsea Football Club has completed the signing of Cristian Cuevas from Chilean club O'Higgins.
"The 18-year-old has signed a contract until 2018. He came through the youth ranks at O'Higgins before breaking into the first team and playing in the top flight in Chile."
Mourinho has already brought in Andre Schuerrle, Marco van Ginkel and Mark Schwarzer.