Manchester City completed a club record deal for Athletic Bilbao defender Aymeric Laporte on Tuesday in a move by Pep Guardiola to bolster the English Premier League leaders' defence for the title run-in.
City tweeted the announcement of the reported £57 million ($80 million, 65 million euros) deal with the message: "Defensive reinforcements acquired!"
The 23-year-old Frenchman is Guardiola's sixth signing of the 2017/18 season and has joined in a deal until 2023.
"I am very happy to be here," Laporte said. "City are a club with a lot of ambition and they are one of the best teams in Europe.
"I am looking forward to working under Pep Guardiola and trying to help the club to achieve success."
Txiki Begiristain, City's director of football, said: "We are delighted to have signed Aymeric. 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."