The Magpies have signed Fernandez from Championship club Swansea in the summer transfer window.
Newcastle manager Benitez has explained why he signed the Argentine centre-back from Swansea in the summer transfer window.
Benitez told The Chronicle: “There are some areas where we need luck because, if we have injuries, we will have some problems.
“We have to manage in the meantime to see if we can fix the problems, but we have to wait because you cannot do everything that you want to do now.
“You have to be sure that the players you have can play in different positions. If you have a problem there, maybe you can use a different one.
“That is why for me to bring in a player like Fernandez gives you more options in other areas.”
Good signing for Newcastle United
Fernandez was quite successful during his time at Swansea, and the former Napoli central defender has proved himself in the Premier League.
Newcastle do needed players at the back, and the former Swansea star is a good signing for the Magpies.
The 29-year-old made 30 starts in the Premier League for Swansea last season and 27 starts in the league during the 2016-17 campaign, according to WhoScored.
Newcastle will be aiming to finish in the top 10 of the Premier League this season.