Chelsea have completed the transfer of Filipe Luis from Atletico Madrid for a fee believed to be in the region of £20m.
The 28-year-old played an integral role in Diego Simeone's side last season, during which they won La Liga and reached the Champions League final.
Atletico's desperation to keep Luis in the squad delayed the negotiations with the Blues, who were informed they had to meet his full £20m release clause.
"Chelsea Football Club can confirm an agreement has been reached with Atletico Madrid for the transfer of Filipe Luis. The move is subject to the 28-year-old left-back agreeing personal terms," estate the London club in its official website.
Meanwhile, Atletico said: "Atletico Madrid and Chelsea have reached an agreement to transfer the rights of Filipe Luis, pending the medical with the English club. The Brazilian footballer had told our club at the end of the campaign his willingness to join the London entity."
Chelsea had already complete the signing of Diego Costa, Cesc Fabregas and Croatian youngster Mario Pasalic while Thibaut Courtois is also expected to return to West London after speneding the last three seasons on loan at the Vicente Calderon.
Filipe Luis will fill the void left by Ashley Cole's move to Roma, with Mourinho left with Cesar Azpilicueta as the only option at left-back position.
Meanwhile, Atletico have signed the Granada full-back Guilherme Siqueira for around £8m as his replacement.