Atletico Madrid have brought Nehuén Pérez to the club from Argentinos Juniors.
The young defender had been playing on-loan with Argentinos Juniors, but was added to Atletico's senior squad on Thursday.
The decision was made due to fitness concerns over defensive pair Stefan Savic and Diego Godin.
Nehuen is Argentina's U20 captain and is currently playing in the South American championship which runs to February 10.
The youngster originally signed for Atletico last summer, but spent the first-half of the season on-loan at Argentinos Juniors.