Rafa Benitez felt Newcastle United were "a bit lucky", yet Jose Mourinho, his long-time rival, didn't begrudge them the three points.
A second-half goal from Matt Ritchie condemned Manchester United to a 1-0 defeat at St James's Park.
The result lifted the club up to 13th in the Premier League table ahead of a two-week break.
There were many talking points. There was Martin Dubravka's performance on his debut. There was also a first goal of the season for Matt Ritchie.
And there was a remarkable defensive performance in the last 15 minutes as Newcastle fought like "animals" to preserve their lead.
Here's your daily briefing:
Newcastle captain Jamaal Lascelles didn't pull any punches after the win.
Lascelles felt some Man United players "went missing" at St James's Park.
"They have got some great players, but I don’t think Man United turned up," said the defender.
“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.”
Dubravka only found out that he was starting a couple of hours before the game.
And the goalkeeper, signed on loan from Sparta Prague last month, didn't let Benitez down.
Dubravka made a superb save to deny Anthony Martial and also turned a deflected Jesse Lingard shot round his post.
The 29-year-old also helped his team through a fraught last 15 minutes.
“He was doing well," said United manager Benitez. "It was his first game, and to keep a clean sheet against Manchester United is fantastic for him.
"But it wasn't just about the goalkeeper. It was about everybody working together and working as hard as they did today and trying to defend.
"At the same time, now, we have more competition in goal, and that's always positive for the team."
Jose Mourinho, Benitez’s long-time rival, warmly congratulated him after the game.
Mourinho had failed to win a league game at St James's Park in six attempts with Chelsea, and he couldn't achieve that feat with Man United.
“He said ‘congratulations and you did well’, more or less what he said before that,” said Benitez.
“The team was working so hard. They had chances, and he could have been thinking that they would score, but the way that we were working, we were doing really well.”
Benitez and Mourinho developed a fierce rivalry after both taking charge of English clubs in 2004.
Mourinho said after the game that it was a “beautiful thing” to watch Newcastle’s players defend as if their lives depended on it in the last 15 minutes.
“I’m not thinking about that (beating Mourinho),” said Benitez. “I was just trying to get three points against anyone, and it just happened to be Manchester United."
Read Mourinho's reaction to the game here.
Islam Slimani has two weeks to prove his fitness after sitting out the Man United game.
Slimani, signed on loan from Leicester City, had hoped to feature after training for much of last week.
However, the striker – who arrived on Tyneside with a thigh injury – didn't make Benitez's squad.
Newcastle now have a two-week break ahead of the January 24 game against Bournemouth at the Vitality Stadium.
Manager Benitez said: “He was fine, but he was still feeling it a little bit.
"It was a case of waiting because we have 15 days now before the next game so we can keep working with him.”