Hertha Berlin have signed Argentina international midfielder Santiago Ascacibar from 2. Bundesliga club Stuttgart on "a long-term deal".
The 22-year-old, who earned the most recent of his three Argentina caps in November 2018, becomes Hertha's first signing since Jurgen Klinsmann replaced Ante Covic.
Ascacibar previously played two seasons of Bundesliga football for Stuttgart prior to their relegation last year and featured 13 times in the second tier this term.
He will join the rest of the squad for their mid-season training camp in Orlando and is in contention to make his debut when Bayern Munich visit the Olympiastadion on January 19.
"I'm happy that the transfer has been completed in the winter break," Ascacibar told his new side's official website.
"After holding talks with [sporting director] Michael Preetz and Jurgen 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 team-mates. We'll do everything we can to keep climbing up the table in the second half of the season."
Hertha, 12th in the Bundesliga after collecting eight points from Klinsmann's opening five matches, are also in the running to sign Granit Xhaka from Arsenal.