Hertha Berlin have completed their first signing since Jürgen Klinsmann took charge as coach, bringing in Argentina international midfielder Santiago Ascacibar from Bundesliga 2 club VfB Stuttgart.
Ascacibar, 22, has signed "a long-term contract", according to the official club statement, and will wear the No.18 shirt.
"I'm happy that the transfer has been completed in the winter break," Ascacibar told the official Hertha website.
"After holding talks with Michael Preetz and Jürgen Klinsmann, I believe I can continue to develop as a player here and that we can achieve a lot together. I'm really looking forward to that and can hardly wait to get to know my new teammates. We'll do everything we can to keep climbing up the table in the second half of the season."
Ascacibar made 13 Bundesliga 2 and two DFB Cup appearances for Stuttgart during the first half of 2019/20. He joined the club from Estudiantes in summer 2017, enjoying two full seasons of Bundesliga football prior to Stuttgart's relegation to the second tier following the 2018/19 play-off defeat to Union Berlin last May.
"Santiago can operate in a number of roles in central midfield," said sporting director Michael Preetz. "At 22 he's a young midfielder with the potential to develop further. He's very strong in the tackle. We're delighted to have recruited another very talented player into our squad."
Ascabicar, who already has 56 Bundesliga games under his belt and is a three-time Argentina international, could make his competitive debut for his new employers when Hertha host defending champions Bayern Munich on 19 January 2020.
The Old Lady are 12th in the Bundesliga, after taking eight points from Klinsmann's first five matches as coach (W2, D2, L1). The former Bayern, Germany and USA boss will remain in the hot seat until the end of the season before resuming his supervisory role at the capital club.