The 28 will be a free agent soon after reaching the end of his contract at Deportivo La Coruña.
The Argentinian defensive midfielder has been given three days to impress Sam Allardyce with view to contract.
Deportivo still have hopes of keeping their player and have offered him a new deal, but the offer by Newcastle and a chance to play in the Premiership could tempt him to Tyneside ... IF he impresses.
He is dubbed "the butcher" by fans in Spain.