AC Milan have completed the signing of Italy defender Leonardo Bonucci from Juventus for €42 million.
Bonucci, 30, has signed a five-year contract at Milan and is reported to have become Serie A's best-paid player.
A statement on the club's official website read: "AC Milan are delighted to announce the signing of Leonardo Bonucci from Juventus FC. The player has penned a five-year contract through to 30 June 2022."
Milan boss Vincenzo Montella said: "He is a player with international experience. Technically, I think that he and Sergio Ramos are the strongest central defenders in the world. Coaching him is a dream come true."
Bonucci has won Serie A in each of the last six seasons with Juve, and also won the league title with Milan's city rivals Inter in 2006.
Milan have enjoyed a hugely successful summer in the transfer market, bringing in Hakan Calhanoglu, Mateo Musacchio, Franck Kessie, Ricardo Rodriguez, Andre Silva, Fabio Borini, Andrea Conti and Lucas Biglia, while goalkeeper Gianluigi Donnarumma agreed a new contract.
However, their efforts to add a further striker have proved more difficult. CEO Marco Fassone said they hoped to sign Pierre-Emerick Aubameyang, Andrea Belotti or Alvaro Morata, but Dortmund said their deadline to sell Aubameyang has passed and criticised Milan's lack of respect, while Chelsea have won the race for Morata.
Earlier on Thursday, Juve signed defender Mattia De Sciglio from Milan for €12m.