The London Evening Standard says Atletico were holding out for the £20m written in his release clause and sent him to train with the reserves earlier this week.
But the Spanish champions are believed to have let him go for £16m with just personal terms to be agreed.
It is understood Chelsea have already offered him a four-year contract worth £78,000 a week and it should be completed soon. He will be free to report for pre-season training immediately because he was not selected for Brazil's World Cup squad, and will follow Atletico team-mate Diego Costa to Stamford Bridge.
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