Spain under-19 international Borja Lopez has joined Monaco from Sporting Gijon.
The centre-back has signed a four-year deal with the newly promoted Ligue 1 side after Sporting accepted a reported 2.2million euro (£1.9 million) bid and was presented at the club on Friday.
He confirmed the signing by posting a photo of his presentation on Twitter along with the message: "Very happy to have signed with Monaco until 2017."
The 19-year-old made 19 appearances for Sporting last season in Spain's Segunda Division A.
A statement on the Asturian club's website read: "The club thank the footballer for his conduct on and off the pitch during his time at the club and wish him every success in the future."
Lopez played every game in Spain's campaign at the UEFA Under-19 tournament in Lithuania in July until they were eliminated at the semi-final stage by France.