Costa has signed a freelance at Atletico however can’t be totally registered till the switch window opens within the New Year.
He transfer will finish a long-running switch saga that noticed him move on strike in Brazil over pre-season.
Chelsea have moved on with out Costa, who’s now coaching with Atletico’s first-team squad with a view to be fit have compatibility for January.
But Atletico supervisor Diego Simeone says the 28-year-old might combat to get into his present aspect, as will winger Vitolo when he returns from his Las Palmas mortgage spell.
“Diego Costa was the chosen player to help return us to the top,” Simeone informed newspaper El Larguero.
“A unique participant of that high quality we possibly may just no longer have enough money to pay however the lovers are keen to peer the similar Costa who left us.
“He brings the whole lot: objectives, onerous paintings, effort and management.
“That being mentioned, I consider Costa and Vitolo will to find it tough to get into our crew particularly once I have a look at the avid gamers we have already got – everybody must earn their position.”
Atletico had been not able to signal Costa in the summertime as they had been below a FIFA-imposed switch embargo that avoided them fielding newly registered avid gamers till 2018.
That supposed Antoine Griezmann agreed to stay on the membership as they couldn’t signal a substitute.
However, Costa’s arrival in January may just spell the tip of Griezmann’s Atletico profession, with Manchester United eyeing up the striker for subsequent time period.
And Simeone remained coy when requested if the January switch window would see extra new avid gamers coming in.
“More January transfers? I would not close the door on anything, arrivals or departures,” he added on El Legarto.