Diego Costa thanked Chelsea for three "remarkable" and unforgettable years as he bid farewell to the Premier League champions.
Costa, 28, will return to Atletico Madrid in January after his move from Chelsea was finalised on Tuesday.
The Spain striker leaves Chelsea in a deal worth a reported €60million after three campaigns, two of which ended with the league title.
Costa thanked the club on Instagram after his move to Atletico was finalised, saying he would never forget his time at Stamford Bridge.
"Some cycles begin while others end," he wrote.
"My cycle at Chelsea began three years ago – three remarkable years in all aspects – and I will never forget it. Two championship titles, a Community Shield, 120 matches, 59 goals and 24 assists later this cycle has ended.
"Not the way I would have wanted – far from it – but the best way possible.
"The wonderful fans of such equally admirable club and all team-mates, as well as all clinical, administrative and logistics staff will remain forever in my mind and in my heart.
"[I] will bring them with me with the certainty that I will always be by their side as well, and I'm sure they will understand the reason why this cycle of mine has now ended – because I could not lose faith in myself. Thank you Chelsea for everything!"
Costa netted 20 league goals in 2014-15 and 2016-17 to lead Chelsea to success, but he fell out with head coach Antonio Conte.
