Jose Mourinho insists Diego Costa is happy at Chelsea, but refused to rule out the possibility of the forward returning to former club Atletico Madrid in the future.
Costa has scored just four times for Chelsea this season and the Spain international admitted in October he was overweight when he returned for pre-season training in the summer.
The 27-year-old, who joined the Blues from Atletico for £32m in July 2014, scored 21 goals for Chelsea last season, but has looked far from the same player this campaign.
His frustrations boiled over when he was dropped for Chelsea's goalless draw with Tottenham in November, throwing his substitute's bib in the direction of Mourinho after warming up on the touchline.
Costa has since apologised for his act of petulance, but threw his long-term future at Chelsea into doubt when he refused to rule out a return to the Vicente Calderon Stadium.
Asked about whether he could return to Atletico on Spanish radio station Onda Cero, Costa said: "You never know."
When asked about rumours that Costa is not settled in London, Mourinho said: "He didn't say that. He said that in football you never know.
"Filipe Luis was one example. He could also say Fernando Torres, another example.
"Atletico is a great club, La Liga is a great league, so why should a 28-year-old player not think it is possible to go back? I don't see a problem.
"He is happy here. He has, I think, three more years under contract. I see him staying at Chelsea for three more years, no problem."