Amongst all the rumours over the summer, Costa still has his heart set on a move back to Atletico Madrid.
Costa is now holed up in his hometown of Lagarto in Brazil and is refusing to return to Chelsea after a major row with manager Antonio Conte at the start of the summer. However, the Spaniard does not appear to have any interest in doing so and the Telegraph claim that he will continue his feud with Antonio Conte rather than return to England.
The saga took another interesting twist this week as clubs submitted their 25-man roster.
The situation gets messier still as Costa has legal proceedings open against Chelsea for "discrimination" as explained by his lawyer in a statement to the news agency EFE. The player, however, remains on strike in his native Brazil.
It was just a message, after everything I did there.
Richard Heathcote GettyImages
"If I was allowed to play five consecutive matches I might have". I said, "If the manager doesn't want me, I want to go to Atletico Madrid".
When a coach picks his players, but you're not included, then what can you do?
What's next for Costa?
Costa has been training alone in Brazil for the past two months. Atletico can still sign Costa outside the transfer window, but he would not be eligible to play until the Madrid team's transfer embargo is over in January.
It was unclear whether Costa would be named in the club's Champions League squad, which was due to be announced at 11pm last night. His side, however, want him to return to Cobham so they can oversee his work.More news: North Korea Nuclear Test Would Be 'Absolutely Unacceptable': Shinzo Abe
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