Jamaal Lascelles says some Manchester United players "went missing" at St James's Park.
A goal from Matt Ritchie gave Newcastle United a 1-0 win over Jose Mourinho's second-placed side yesterday.
Newcastle captain Jamaal Lascelles said: "They have got some great players, but I don’t think Man United turned up.
“We've played against Arsenal and Man City, and you can really see the quality, and one mistake or a lack of concentration and a goal will go in.
“I don’t think they were at it from the start of the game – a lot of their players went missing.
“It was probably the way we were playing. We made them play like that.
“In the first half, they were making a lot of mistakes, passing the ball around, but it was down to our pressing.
“We were aggressive and they didn’t like it. You could see their centre-halves on the ball, and they didn’t really know what to do with it.
“We set up really well and we matched up really well against them. The manager (Rafa Benitez) got it spot on.”
The result lifted the club up to 13th in the Premier League.
“It was a huge win, but it wasn’t a shock for us," said Lascelles. "Most games we have played this season, we have been really good.
“Man United have some world-class players, but it seemed like we just wanted it a lot more.
"With the bigger teams, teams like us will always want it a lot more, and their quality wasn’t enough to beat us and our hard work and endeavour was enough to get us over the line.”
Lascelles felt that manager Rafa Benitez got his tactics "spot on".
“All week the manager had been working on how we can beat these guys, and we stuck to his tactics and got it exactly right," said the 24-year-old.
“We can’t go to toe-to-toe with these teams and try to play football – it's not going to happen.
“What we can do is work hard, make it nasty for them and try to make them play how we did and I can only praise the boys for that today.”
Ritchie's goal was his first of the season.
The "frustrated" winger – who scored 16 goals last season – had been struggling for form.
“Matt has been pretty frustrated recently, but he finally got his goal, and hopefully he can start finding the net a bit more often," said Lascelles.
“But overall, a massive team performance and man of the match could have gone to anybody.”