"Subject to the completion of the deal Mateo Kovacic will join the Blues on a season-long loan".
The teams didn't disclose terms of Courtois' transfer, but multiple outlets report Real Madrid will pay Chelsea £35 million (€39 million/$45 million) for his services.
The Belgian will leave Chelsea after seven seasons, three of which he spent on loan at Atletico Madrid.
'It's a very important decision for me, for my career, and also for my personal life, ' he said.
The goalkeeper arrives as the club's record signing and the most expensive stopper in world football. He helped the Blues win two Premier League titles, one FA Cup and one League Cup during his time at Stamford Bridge.
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Yesterday, Firefighters had managed to contain 41 per cent of the Carr blaze, and authorities were letting some evacuees return. The fire burned slowly for days before winds suddenly whipped it up last week and drove it furiously through brush and timber.
A statement read: 'Kepa, who is eligible to play in Saturday's Premier League opener against Huddersfield, will train with his new team-mates for the first time tomorrow'.
Chelsea's imminent world-record deal for Athletic Bilbao goalkeeper Kepa Arrizabalaga has paved the way for his exit, allowing him to move for a reported £35million as Croatia midfielder Kovacic heads the other way.
"The aforementioned certification states that the player has expressed his willingness to unilaterally close and terminate the relationship between them since the 2004/05 season and that the amount of compensation established in the contract has been deposited".
Chelsea had also considered raids for Jack Butland, Sergio Rico and Jan Oblak as they sought to replace the departing Courtois.
He becomes the third acquisition of a chaotic summer transfer window for Chelsea, following the £50m capture of Jorginho from Napoli and the signing of third-choice goalkeeper Robert Green on a free transfer.