The deal is expected to be on loan with an option to buy at the end of the 2015-16 season, with Spurs attempting to recoup the €35.5 million they forked out for him whilst at Roma.
The Argentinian managed two goals in his 45 appearances since 2013 in the Premier League, just a fraction of what he achieved back with the Giallorossi, in which he scored 19 goals in 62 showings.