Chelsea have completed the signing of Lokomotiv Moscow defender Branislav Ivanovic on a three-year-deal for an undisclosed fee.
Ivanovic becomes Avram Grant's second January signing
A work permit for the 23-year-old, who was also a target for Manchester United, had already been granted.
Serbian Ivanovic passed a medical and finalised personal terms, with the transfer fee thought to be almost £9m.
"It is the dream of any player to improve and the ultimate is to play for such a big team as this," he said.
Ivanovic can play anywhere in defence and won his first senior cap for Serbia and Montenegro in June 2006 in a friendly against Italy.
He is now a regular in the Serbian line-up alongside Manchester United's Nemanja Vidic and has made nine appearances and has scored once.
Blues manager Avram Grant has also signed Nicolas Anelka from Bolton in the transfer window.