The Daily Star says the Blues are close to wrapping up the transfer of Costa but want Luis included in the deal to bring down the asking price.
It is understood Chelsea value the pair at around £40m - and are trying to offer players in part exchange.
But Atletico claim that is unacceptable as they rate Luis at almost £20m, while Costa has a release clause of £32m.
Chelsea are willing to offer Romelu Lukaku as a makeweight but the Spanish club insist he is not high on their transfer wish list.
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