Fernando Torres is returning to Atletico Madrid on loan until the end of the 2015-16 season.
The Chelsea striker will join current loan club Milan on a permanent deal on January 5 before immediately returning home to Madrid, where he came through the ranks to become Atletico captain earlier in his career.
And Torres, who scored just 20 goals in 110 games for Chelsea following a £50m move from Liverpool, says he is going back to his roots "in pursuit of happiness".
"When I was a child, my dream was to play for Atletico," he said. "I achieved that, and to come back now is another dream I get to accomplish again. I've been fine with other teams, but there isn't one like Atleti.
"Nobody can doubt how I'll feel wearing that shirt again. Atleti fans always demand your all on the field and I guarantee that I will give them that and more."
Torres left Atletico for Liverpool in July 2007 and enjoyed three-and-a-half productive seasons on Merseyside before leaving for Stamford Bridge.
The goals dried up in London and, despite important contributions during the club's Champions League and Europa League-winning runs, he was loaned to Milan in the summer for the remainder of his contract.
Just 10 games and one goal later he is going back to Spain, and a statement from Atletico read: "He returns home, where he trained as a player and became one of our biggest stars."
Torres made more than 200 appearances for Atletico after making his debut in May 2001.
He scored the only goal of the Euro 2008 final for Spain against Germany and was a substitute two years later when they beat the Netherlands in the final of the World Cup.