Chelsea striker Diego Costa says he cannot rule out the prospect of a return to Atletico Madrid.
The 27-year-old has struggled for form during the Premier League champions' inconsistent campaign so far, scoring just four times in 19 appearances.
Talk of a falling-out with manager Jose Mourinho has instensified speculation that the Spain international could be sold as early as January, with former club Atletico touted as a possible destination.
And Costa has pointed to former team-mate Filipe Luis, who left Chelsea to return to the Vicente Calderon after just one season, as proof that his own future is tough to predict.
"I don't know if I'll go back to Atletico. Life always takes plenty of twists and turns. Look where Filipe Luis is," he told Onda Cero's Al Primer Toque.
"The truth is that I want the best for Atletico, I always cheer them on from afar.
"It would be better not to meet Atletico now, they're a very uncomfortable team to play. I want the best for them. If I could choose, I want to face them in the [Champions League] final."
The 27-year-old was dropped by Mourinho for the 0-0 draw with Tottenham and petulantly threw his bib in the direction of the manager, prompting further speculation that his relationship with the Portuguese was untenable.
But Costa himself has denied the suggestion, saying: "Our relationship is exciting, we got along very well. There are things I have to control, but it [throwing the bib] was an impulse."
Costa acknowledges he has to demonstrate an upturn in form during the second half of the campaign if he is to ensure a place in the Spain squad for Euro 2016, however.
He said: "I have to improve. The start of the season hasn't been good for me, either in play or in goals. I know I have to improve so that [Spain coach Vicente] Del Bosque calls me up for the Euros. I have to work and fight."
Costa was fortunate to escape with just a yellow card when he deliberately tripped goalkeeper Iker Casillas during Chelsea's 2-0 win over Porto on Wednesday, but the striker is adamant it was nothing serious.
"Nothing happened with Iker," he added. "I went to make a little joke, he got a bit angry, but that's it. There are no problems with him. Why would I look to make trouble with the national team captain?"
