Sky Sports understand that Real Betis have agreed to an initial €500,000 offer from Boro, although with add-ons including possible promotion to the Premier League the deal could go as high as €2million.
Boro are hoping to persuade the 25-year-old, who played over 30 games in La Liga last term, to make the move to the North East.
Right-sided Juanfran, who can also as a winger, joined Betis last summer after four years with Madrid. While most of that was with their B team Castilla, he did manage one game for the Real first team.
Speaking to the player's agents Poromosport, they told Sky Sports that no deal was agreed with Boro and that offers from other clubs also existed.