Borussia Dortmund have signed former Liverpool target Manuel Akanji from Basel for a reported €21.5 million fee including bonuses.
Akanji, a former target for Liverpool, became the club's first signing of the January transfer window when he agreed a deal until 2022.
The Switzerland international defender was in Dortmund on Sunday to witness the club's goalless draw with Wolfsburg and a day later put pen to paper on his contract.
"With his performances, Manuel appeared on the radar of several European top clubs," Dortmund sporting director Michael Zorc said on the club's official website. "We are delighted that he opted to join us.
"He's shown for his national team and in Champions League that he can play at the highest European level. At the same time, we believe he's a defender with still a lot of potential for development."
✍️ Borussia Dortmund hat sich mit dem @FCBasel1893 auf einen sofortigen Wechsel des Spielers Manuel #Akanji verständigt. Der 22 Jahre junge Abwehrspieler unterzeichnete einen Vertrag bis zum 30. Juni 2022 und erhält die Rückkennummer 16. Herzlich willkommen, Manuel! ✌️ pic.twitter.com/79VFrXKz9I— Borussia Dortmund (@BVB) January 15, 2018
Akanji has so far won four caps for Switzerland, and has impressed during Basel's Champions League campaign this season.
The defender said: "I felt good in the talks with the BVB hierarchy. And thus, my heart decided. I have always liked the football played by Dortmund. I am looking forward to my time here, and will give it my all."
After boasting the best defensive record in Europe's five top flights with two conceded goals in seven matches up until the first international break in late September, Dortmund conceded 22 goals in just 10 league games up until the winter break.
They now rank 43rd among the 98 teams of Europe's top flights.
Under new head coach Peter Stoger, Dortmund have managed to stabilise their defence, conceding only one goal in the former Cologne man's three matches in charge.
Dortmund are set to pay just under €20 million for Akanji, according to kicker, with Sky adding that the transfer fee could go up to €21.5 million with bonuses.