Kevin-Prince Boateng has moved from Sassuolo to Barcelona on a loan deal for the rest of this season.
The deal for the 31-year-old also includes a $9 million option to buy on a permanent basis.
Sassuolo hailed the link between the two clubs.
"This furthers the profitable relationship between Barcelona and Sassuolo, born this summer as part of the buying and selling of the footballer Marlon. The Catalan club thank the Italian club for their openness in conducting these negotiations. The Italian club, on their part, express how very proud they are to be able to continue this relationship with one of the biggest and most prestigious clubs in the world."