Both clubs announce deal on Thursday for Brazil-born forward's return to Spain until 2021
Chelsea and Atletico agree terms over Diego Costa
Chelsea and Atletico Madrid announced Thursday that they had reached an initial agreement that would see Diego Costa return to the Spanish club.
"Atletico de Madrid and Chelsea have reached an initial agreement for the transfer of Diego Costa," the Spanish side said in a statement.
"The agreement is pending the formalisation of the contract between our club and the Spanish international forward.
"The English club has authorised Diego Costa to travel to Madrid in the coming days to undergo medical tests and settle his contract with our club."
Chelsea said they had "agreed terms with Atletico Madrid for the transfer of Diego Costa".
"The transfer will be subject to the agreement of personal terms and a medical."
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Costa, 28, has been frozen out by Chelsea manager Antonio Conte and spent the transfer window angling for a return to former club Atletico that never materialised.
Sports dailies Marca and Mundo Deportivo earlier said the two clubs had sealed a deal for the Brazil-born forward's return to Spain until 2021.
The deal was worth €60 million (Dh262.7m), according to AS, while Marca said Atletico will pay €55m with a further €10m in add-ons.
Costa will not, however, find himself straight back in action, with Atletico officially banned from registering new players until January.
Costa was not included in Chelsea's 25-man squad for the Champions League group phase, ironically drawn in Group C along with Atletico. That ensured he would not become cup-tied and therefore remains free to play in the competition for another team in the second part of the season.
The reported transfer fee smashes Atletico's record of €40m paid for Radamel Falcao in 2011.