Sosa – who has played for Bayern Munich and Napoli during his career – has spent the last three years at Metalist.
But a six-month loan deal to European football looks to have been confirmed after the Ukrainian club released a statement on their official website.
"FC Metalist captain Jose Sosa received permission from the club president Sergiy Kurchenko to go on six-month loan to one of the European clubs," the statement read.
"We listened to Jose Sosa's request that he wants to win a place in the Argentina national team to participate at the World Cup in 2014, which will be held in Brazil.
"Given Jose's contribution to the development of the club and taking into account the fact that the championships in European countries are held during the winter, in contrast to Ukraine, we have decided to meet Sosa's wish to go on six-month loan to one of the European clubs.
"I should note that during this period we will purchase new quality players for our club in order to achieve our goal - the conquest of the championship and the cup of Ukraine.
"FC Metalist awaits the return of Jose to the club and is sure that this player will bring many benefits to our team in the future."
Speculation over Sosa's future has grown in recent weeks, with the club in question believed to be Atletico after the player's agent, Ezequiel Manera, apparently announced the deal on Twitter.
"Jose Sosa will play for Atletico on loan for the following months with an option for them to then buy him," read a message posted on an account purporting to belong to Manera.
The attacking midfielder is expected to officially join Atletico when the transfer window reopens on Wednesday, with a presentation to the club's fans to follow.
The Argentinian made seven appearances in his country's qualification for the 2014 FIFA World Cup but has not played in the UEFA Champions League this season and will boost Diego Simeone's squad for the round of 16 tie against Milan.
