Fernández joined the Magpies from Swansea on Thursday afternoon, penning an initial two-year deal with the club.
It reunites the defender with Benítez, who Fernández played under at Napoli, where they won the Coppa Italia and the Supercoppa Italiana together.
And the Argentina international is looking forward to once again working with the Spaniard at St. James’ Park.
“We were working for one year in Naples and it was really good. I had a great experience, won trophies in Naples, and he was the key to my move to Swansea as well,” the 29-year-old told NUFC TV. “He told me about the Premier League and the club, and it was very important. We found a way to work together, and now him and the staff are working really hard to improve the players and the team, so it’s something that is really good for everyone at the club. I’m really excited to work with him again.
“At that time in Naples I was 23 so I learned a lot under Rafa. I had the chance to come to the Premier League, and now he believes in me because he knows what I can do for the club and the team. I like the way they work so I try to show my best for the club.”
The last Argentinian centre half to play for Newcastle was Fabricio Coloccini, who enjoyed an eight-year spell on Tyneside after arriving from Deportivo La Coruña in 2008.
“I had the opportunity to play with Fabricio in the national team, and I know about the years he spent at Newcastle.” said Fernández. “He was a great player for the club, and I hope I can do the same like him. Maybe in the future I’ll have the opportunity to speak with him and he’ll tell me more things about the city and the club. During the week, I will contact him, 100 per cent.”
Fernández brings considerable experience with him to Newcastle, having amassed over 100 top flight appearances for the Swans after playing in the Champions League at Napoli.
He was also a World Cup finalist with Argentina in 2014, and he is hoping his new teammates will be able to benefit from his nous.
“I already had four years in the Premier League. It’s something I have and I need to show on the training ground my experience and help the youngest, and start to improve the team,” he said. “We are here to play in the same team so I’m looking forward to training right now and the season ahead. With my experience, I hope they can trust me on the pitch.
“I know it’s a really good squad, with very good spirit in the team – you can see that from outside. That’s a good thing in the dressing room, and when you play against Newcastle the atmosphere here is great, so I just want to show my ability to help everyone in the squad.”
