Chelsea have signed midfielder Tiémoué Bakayoko from Monaco on a five-year contract.
The €45million (£39.7m) deal for the 22-year-old was sealed on Saturday.
“I am very happy to be here and to join this great team. I have grown up watching Chelsea,” said Bakayako, the club’s second-most expensive signing.
“Signing was the natural thing for me because it is a club I loved very much in my childhood.
“I am now looking forward to evolving under this fantastic coach and alongside so many great team-mates.”
The Paris-born midfielder, who graduated from Rennes Academy, was a key figure for Monaco as they won the Ligue 1 title and reached the Champions League semi-final last season.
He scored the goal which eliminated Manchester City in the last 16 of that competition.
“Tiemoue was outstanding as Monaco emerged as one of Europe’s best sides last season and we are delighted to welcome him to Chelsea,” Chelsea’s technical director Mike Emanalo said.
“Despite his young age he already has plenty of experience as a French title winner and having competed in the latter stages of the Champions League, we believe he will add considerable quality to our squad.”
Bakayoko may have to wait until September to make his debut after undergoing a knee surgery in the off-season.