The 19-year-old full-back has been a key player for Los Che this season despite his age, and has played a big role in the team’s outside challenge for the La Liga title.
He’s considered to be one of the best young players in Europe in his position, which has alerted Chelsea.
Jose Mourinho is yet to be convinced by summer signing Filipe Luis, who has barely featured despite costing the Londoners big money last summer.
The former Atletico Madrid man could be used in a like-for-like swap deal with Valencia this summer, although they may have to match his £13.6m release clause to get a deal done.
Gaya rejected a new contract offer from the Mestalla outfit last week, which would have more than doubled the figure needed for his services.