Chelsea will have to pay Jan Oblak’s €120 million (£110m/$137.5m) release clause to force contract talks with the Atletico Madrid goalkeeper.
It remains unclear whether the 27-year-old would be ready to leave Atletico this summer, with manager Diego Simeone ready to block the exit of the Slovenia international in most circumstances.
However, the relationship between Chelsea and Atleti is good, having seen the transfers of Diego Costa, Alvaro Morata and Thibaut Courtois conducted between clubs in recent seasons.
Blues boss Frank Lampard remains unconvinced with his goalkeeper Kepa Arrizabalaga, and he would need to find him an escape route to try to balance the books before considering such an offer for a player such as Oblak.
Valencia have recently enquired about possible arrangements to sign Kepa on loan, as they look to move on their current No.1, Jasper Cillessen.