The London Evening Standard says Chelsea are determined to send out a signal of intent during the transfer window and finalise most of their business early in the summer.
Talks with Atletico over Costa and left-back Filipe Luis have been ongoing. Both players are expected to complete their moves to Stamford Bridge, but the total fee for the pair has been an issue.
Former Chelsea midfielder Tiago Mendes, who is going to return to Stamford Bridge from Atletico as a free agent, has played a part in convincing the duo to move to west London.
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