Ciaran Clark headed Steve Bruce’s side in front at the London Stadium before Fernández nodded in United’s second in what was a dominant first half display from the visitors.
Jonjo Shelvey’s long-range free kick made it 3-0 after the restart, and though Fabian Balbuena and Robert Snodgrass pulled a couple of goals back for the hosts late on, Newcastle held firm to claim the points.
Fernández – who provided the assist for Jamaal Lascelles’ opener against Wolves last weekend – turned in another solid display at the back on his second start of the campaign.
And after bagging his first goal in black and white the 30-year-old said he made the most of the celebrations, after heading over to the travelling Magpies faithful to share what proved to be one of the game’s crucial moments with them.
“I think the key point is that we scored the goals at the right moment,” he told nufc.co.uk. “Obviously they came and left a space in behind, and we knew that if we put a ball behind their defence we had a very good chance. We did, and for me the most important thing is create chances, putting the opposite team in a difficult situation.
“It’s been a great two games, and I’m really happy to score the goal. I’m happy because we really needed these three points too in front of the fans. (For) the three thousand who came tonight, it was a brilliant game for them to come and watch.
“I don’t score very often so I needed to celebrate this one as much as I can! It was in the right place, in front of the fans, so that was really, really good.”
On his team’s superb showing in the opening 45 minutes – which also saw Miguel Almirón, Allan Saint-Maximin and Shelvey go close – Fernández added: “The first half was unbelievable, with the two goals, and we created two or three clear chances in front of the keeper, so it could have been three or four.
“That’s what we’re looking for with (Miguel) Almirón and (Allan) Saint-Maximin – that when we recover the ball, they have big pace to do that. I’m really happy for all of them.”
Balbuena’s close-range finish and Snodgrass’ volley made the scoreline look a little kinder to Manuel Pellegrini’s Hammers.
And despite the hosts’ late spell of pressure, Fernández said he felt “100 per cent” sure United would emerge with the points.
“In the second half we worked hard,” he said. “We knew what we needed to do in defensive shape as well, and when we needed to drop a bit more. 3-0 is a big (score) but they came, they pushed us and started to put balls in the box, but we dealt with this. I think overall it was a great, great performance from everyone.
“For confidence, it’s very important. We were really good in terms of defensive shape, and in the last couple of weeks we have been working more on keeping the ball and going forward. I think in the last two games we have done this a little bit better."
He added: “Now we have another home game (against Bournemouth), so we need to be 100 per cent ready and play the same way, with the same intensity, to try to win two games in a row. That would be massive for us before the international break.
“We need to understand that this game will be good for us – but as well, we need to work hard and be ready for the next one.”
