Agent Alberto Toldra said "Negotiations are very advanced with Middlesbrough, we are talking to Lazio this morning and it could all be resolved in the next few hours."
Atletic Madrid and Athletic Bilbao were also said to be tracking the highly regarded player, but Lazio president Ugo Longo said "Middlesbrough have shown more interest in acquiring Gaizka Mendieta and are the prime candidates to get the player. Mendieta's future will be resolved by the end of the week."
Latest: Boro confirmed this afternoon that talks were ongoing with Mendieta.
With the transfer window closing in less than two weeks it is vitally important that Boro strengthen the midfield area.
Boro must also wait to speak to their other target, Fulham's Sean Davies. The South London club will not allow clubs to talk to the want-away midfielder until a replacement is signed.