MADRID: French teenager Theo Hernandez became the first player to cross the divide between Atletico and Real Madrid in 17 years on Wednesday, as the clubs confirmed they had reached an agreement which local media reported to be worth around 30 million euros ($34 million).
The left back's brother Lucas plays for Atletico, and their father Jean-Francois also turned out for the club.
The last player to transfer straight from Atletico to Real was Argentinean midfielder Santiago Solari in 2000.
On that occasion, the former had been relegated from Spain's top flight.
But the latest deal will come as a bitter blow for manager Diego Simeone and Atletico, who last month saw their appeal against a transfer ban for the illegal signing of minors rejected by the Court of Arbitration for Sport. Atletico cannot register new players until January 2018.
"The player, who was contracted until 2021, has rejected numerous offers of a new deal from Atletico and other European clubs, reiterating his desire to play for Real Madrid," Atletico said in a statement.
The France Under-20 international joined Atletico in 2008 aged 11 but never made a first team appearance for the side.
He impressed on loan at Alaves last season, making 32 La Liga appearances for the Basques and scoring a stunning consolation in the 3-1 King's Cup final defeat by Barcelona – ironically at Atletico's old Vicente Calderon stadium in his only competitive appearance there.
The deal is representative of a shift in transfer policy from Real Madrid president Florentino Perez in favour of younger players, including Hernandez and Jesus Vallejo, with recent Euro Under-21 player of the tournament Dani Ceballos reported to be next on the agenda at the Bernabeu.