Chelsea have sold defender Filipe Luis back to Atletico Madrid, the Barclays Premier League club announced on their website.
The 29-year-old Brazilian, a £16million signing from Atletico last summer, returns to the Spanish capital after making only 26 appearances for the Blues.
" We wish him all the best for the future," a club statement read.
Luis has signed a four-year-contract with Atletico for a reported fee of £11million.
Of his 26 appearances for Chelsea, only nine of them were starts in the Premier League after he struggled to displace Cesar Azpilicueta at left-back.
Luis returns to Spain with Premier League and Capital One Cup winners medals and scored once during his year at Stamford Bridge.