Barcelona are targeting Athletic Club defender Unai Nunez and have reportedly made 'informal contact' with the 20-year-old's representatives as they seek to revamp their defence in the not-too-distant future.

With Javier Mascherano ageing and Thomas Vermaelen unable to stay fit for long periods, Ernesto Valverde's men are looking to add some youthful quality to their backline. Both the Argentine and Belgian's future at the Camp Nou are rather uncertain; Mascherano is considering his options while Vermaelen was of interest to Premier league outfit Everton in the summer.

Napoli defender Kalidou Koulibaly, who has developed into one of Europe's most well-rounded centre-backs under the tutelage of esteemed manager Mauricio Sarri, recently emerged as a target for the Blaugrana, while Palmeiras star Yerry Mina is expected to join in the next few months for around £8m.

Recent reports suggest that Napoli are prepared to cash in on Koulibaly if they receive an offer worth £53.5m, but Spanish outlet Sport claim that Nunez is another star under consideration at the Camp Nou. Barcelona apparently see the Spain Under-21 international as a "future option" for their defence, and have already sounded out the player's advisors.

Nunez has established himself as an important part of Athletic's backline already this season and has featured in all eight of his side's La Liga fixtures. José Ángel Ziganda's side have started the new campaign in disappointing fashion and currently languish in 11th place, but Nunez has caught the eye of many with his intelligent reading of the game and ability to play out of defence, including former Athletic manager Valverde, who has enjoyed a rather encouraging start to life as Barcelona boss.

Nunez's advisors were apparently delighted to hear of Barcelona's interest, though they are aware the best thing for the young Spaniard is to cement his place at the San Mames and concentrate on his development, which will predictably be in sharper focus because of Barcelona's engrossment.

Unai Nunez
Nunez has garnered admirers after an impressive start to the season. Getty Images