The 25-year-old midfielder moved to Benfica in January 2011 as part of the deal that brought defender David Luiz to Stamford Bridge.
I have played my last game here
Matić was linked with a surprise return to west London over the summer after impressing since his switch to Benfica.
The Serbian has scored three goals in 20 appearances in all competitions for Benfica this season, prompting renewed reports of a switch to the Blues.
Out-of-favour Chelsea midfielder Kevin de Bruyne is expected to seal a return to the Bundesliga in the coming days, with Matic set to move to Chelsea.
And the Benfica star fuelled speculation by claiming that he had played his last game for the Portuguese club.
“I have played my last game here. I want to improve, I want to go to a better league and I want to go to Chelsea, the club which I also love,” Matić said.
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