Costa determined to rejoin Atletico
The Brazilian-born Spain international, who joined Chelsea from Atletico in 2014, has accused the club of treating him like a "criminal".
Costa has not played for Chelsea since the FA Cup final in May, following which he claims manager Antonio Conte sent him a text telling him he was not in his plans for the new season.
The Brazilian-born Spain international, who joined Chelsea from Atletico in 2014, has accused the Premier League club of treating him like a "criminal" and has said he was willing to see out the remaining two years of his deal unpaid in Brazil.
"My destination is already set," Costa was quoted as saying by Brazilian newspaper O Globo. "I must return to Atletico Madrid next season."
The situation is complicated by the fact that Atletico are currently banned from signing players in this window although a loan deal would be possible. The club have been handed a two-window FIFA transfer ban for signing minors.
"It turns out that there is the impasse that Chelsea does not want to release me," added Costa. "But I believe this situation will be resolved now on my return to Spain."