Jeremie Boga has left Chelsea and joined Sassuolo on a permanent deal.
The 21-year-old leaves for Serie A having made one senior appearance for Chelsea.
And the Blues have confirmed the midfielder will move to Serie A, although they have a buy-back clause inserted in the deal.
A club statement read: “He helped us lift two FA Youth Cups, the Uefa Youth League and Under-21 Premier League during his time as a Blue, as well as spending time on loan with Rennes, Granada and Birmingham City.
“We thank Jeremie for his service and wish him well in his future career.”
After helping Birmingham narrowly avoid relegation, Boga insisted he was desperate to play regular first-team football without going on loan.
He said: “The goal has been achieved, we managed to save ourselves. We had ups and downs. I only remember the positives.
” I have clear ideas about my future. This is my third season on loan.
I have a lot of experience and I feel ready for next year to either fight to try to establish myself at Chelsea or to leave the club.
I do not really want another loan”