The Turkey international has found the going tough in the early part of his career with the Blues following his £27million January switch from Besiktas, with boss Sam Allardyce deciding to drop him to the bench after just two starts.
Allardyce has commented several times that the 26-year-old is struggling to adapt to the English, while reportedly he has been so unimpressed that he is considering sending him back to Besiktas on loan in the summer.
The Turks would appear keen to have Tosun back given how prolific he was before his switch to Merseysidse and Besiktas official Metin Albayrak says he remains in contact with the striker.
"Cenk Tosun is like one of our sons," said Albayrak.
"We have a special place in our hearts for him. Yes we are still in contract with him and if he tells us he wants to return our door is open. I am, however, sure he will return to form."