Freshly arrived in Madrid, José Sosa passed his medical on Thursday and is set to begin his six-month loan spell at Atlético.
The Metalist attacking midfielder had previously played for countryman Diego Simeone when ‘El Cholo’ coached Estudiantes.
Together, they won Argentina’s top flight’s Apertura title in 2006.
Simeone’s long-time interest in acquiring the 28-year-old has been reported on often, and his arrival to the Spanish capital may push Léo Baptistão or Cristian ‘Cebolla’ Rodríguez out on loan.
Known as ‘El Principito’ (The Little Prince), Sosa has previously spent time with Bayern Munich and Napoli, in addition to Estudiantes and Metalist.
The Argentina international (19 caps), who is known for his free kick ability, will be presented at the Vicente Calderón on Friday.
“The truth is, I am happy about arriving here and having passed the medical, and I am eager to start training with Atleti as soon as possible,” Sosa told reporters following his check-up.
“This is an important club that is experiencing a good moment and it fills me with pride to belong to a team and to a fan base that is surely enjoying the team’s great moment.”