Manchester City have announced the club-record signing of Aymeric Laporte from Athletic Bilbao in a deal thought to be worth £57m.
The 23-year-old overtakes Kevin De Bruyne as the Citizens' most expensive arrival after his release clause was triggered over the weekend.
Laporte, who has yet to be capped by France at senior international level, has been handed a five-and-a-half-year contract at the Etihad Stadium and will sport the number 14 shirt.
City's director of football Txiki Begiristain told the club's official website: "We have assessed defensive options and he is a player we have admired for a long time.
"With his quality and ability to play out from the back, we feel Aymeric will fit in perfectly with Pep Guardiola's playing style."
City have been in the market for a new centre-back since the summer after missing out on the signing of West Bromwich Albion's Jonny Evans.
Laporte's arrival may now pave the way for Eliaquim Mangala to depart on loan for the remainder of the season.
