Diego Costa shows off his new Atletico Madrid kit for the first time... on the day his current club play the team he left behind in the Champions League

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Diego Costa is back in Atletico Madrid colours and he wants the world to know it.

The striker, whose move back to his former club from Chelsea was formally completed this week, has been pulling on the Atleti kit for the first time since his return.

And he was quick to post a snap of his shorts, bearing the club crest, onto his Instagram story. 

Diego Costa has shared a picture of himself in Atletico Madrid colours for the first time

Costa returned to Atletico to watch his new team-mates beat Sevilla on Saturday

Costa, who passed his medical at Madrid on Monday, will command a £58million fee when he makes the permanent switch in the summer - he will first join Atletico on loan until the end of the season.

And, though he cannot play for his new team until January 1 due to Madrid's existing transfer ban, he is quickly settling into life at the Wanda Metropolitano. 

His post comes less than 24 hours after he stuck an emotional message up on his Instagram page, thanking the Chelsea fans for their support during his time at Stamford Bridge.

Next to a picture of himself kissing the Premier League trophy, he wrote: 'Some cycles begin while others end. My cycle at Chelsea began three years ago – three remarkable years in all aspects – and I will never forget it. 

Costa's move is initially a loan until the end of the season before becoming permanent

'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. 

'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!'