Fernández featured in the Magpies' 2-2 draw at Bournemouth a fortnight ago, a first start for the Argentine since Newcastle's Boxing Day defeat at Liverpool.
The 30-year-old will look to keep his spot in United's back four for their away clash with the Gunners whilst aiming to build on their momentum from positive results against Everton and Bournemouth, with Rafa Benítez's side coming from behind in both Premier League meetings.
Newcastle sit in 13th place on 35 points - seven points clear of the relegation zone - and Fernández believes the team spirit recently shown from the Magpies will be key in their trip to North London.
Fernández told nufc.co.uk: "The international break was good to have a rest with the family but, at the same time, you are thinking you are wanting to play as soon as possible. We are back at the training ground and preparing this week ahead of facing Arsenal.
"Everyone in the squad are high in confidence but, obviously, we need to be working hard every single game to try and get points as soon as possible to be in a good position for the last couple of games.
"There is a great belief in the team. Earlier this season, it wasn't as strong as it currently is. Against Bournemouth, everyone was pushing really hard until the last minute and we must be fully focused for the final seven league games to be sure we can stay in the Premier League.
"A positive result can help us to move further up the table but an away game against Arsenal is always difficult. They are a good side and we will need to be together as a team like we have been in the last few months, working hard and being able to play football when we can and create chances.
"We are close but nothing is done yet. The next few games will be very important for us and hopefully we can try to win those games to finish as high as we can."
After reclaiming his centre-back spot against the Cherries, Fernández was disappointed in the timing of the international break, immediately after his return to the starting line-up.
And, after starting in 13 of United's opening 16 league fixtures, the defender remained upbeat of his chances to solidify his place in the Newcastle backline.
He added: "It is a little bit frustrating to wait two weeks for your next game because you want to be playing every week. That's part of the international break though and you can't do anything about that.
"Everyone during the season has many opportunities to play a lot of games, which is good. When you don't play, you are trying to train well so you can be ready when the opportunity comes for you and be able to show on the pitch you can help the team.
"Everyone is fit and there is a lot of competition in defence. We are lucky to play for this club and in the Premier League. Whether you are playing or on the bench, you try to continue training well and, in football, injuries and suspensions can affect that and you could play every week.
"As professionals, we must show that you are ready when the manager decides to selects you that you can do it."
