Madrid - Spain striker Diego Costa claimed he was coming home after completing his return to Atletico Madrid from Chelsea on Tuesday.
Both clubs finally reached an agreement for a reported initial €55 million deal on Thursday and the Brazilian-born striker has now completed his medical with the Spanish giants.
"I'm very happy to return home, I've always said it, Atletico is my home, I'm very, very happy," he told the club's website.
Costa can't feature until January as his move was completed outside the transfer window.
However, Atletico said he will begin training immediately and is likely to be in the stands when Chelsea are the visitors for the first ever Champions League game at Atletico's new Wanda Metropolitano on Wednesday.
"The international forward signed his new contract after successfully passing the medical tests that he underwent in two phases: last Saturday and Monday," Atletico said in a statement.
"Starting tomorrow, he will join the team's training, but he will not be registered until the next winter market opens on January 1st."
Costa was Atletico's top scorer as they won La Liga and reached the Champions League final in 2013/14 before moving to Chelsea where he won two Premier League titles in three seasons.
"I'm looking forward to start contributing. I'm going to give my all for the team, as I always try to do," added Costa, who will wear the number 19 jersey.