The 25-year old Serbia international, who left Stamford Bridge for Portugal in 2011, will reportedly undergo a medical at Cobham on Tuesday before re-joining the Blues for around £22million.
Defensive midfielder Matic, who was used as a ballast for Chelsea to land David Luiz in January three years ago, but will now head back to southwest London and according to The Guardian, will sign a three-and-a-half-year deal.
However, the player himself was non-committal on the move when quizzed by A Bola: "I still can't say anything about this, let's see what happens in the future, you have to ask the club and the president.
"If it's good for the club and for me, we'll talk. Let's see what happens until 31 January."
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