The 19-year-old was a surprise inclusion in Steve Bruce's starting XI but the manager's faith paid off when he beat David de Gea from long range to secure three points.
Normally it's Sean Longstaff who makes the headlines at St James' Park, but Sunday was all about his little brother.
After a dream debut, Matty must have been on cloud nine and shortly after, both siblings were sent out by their manager to give the post-match interview to Sky Sports.
And what an interview it was.
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The teenager was asked to sum up his emotions on what was a huge day, while his brother explained exactly what the atmosphere was like in their house the night before the fixture.
Fair play to Sky Sports as well, because the interviewer never once made the discussion about United's terrible run of form.
Instead, he focused purely on what was a special day for the Longstaff brothers. Check it out below.
How heartwarming is that? It's wonderful to watch and you can see just how much it means to them both. Passion and glory, that's what football is all about.
This is the kind of win that can change Newcastle's season, too. After a disappointing start to the campaign, the Toon have now pulled themselves out of the relegation zone.
In fact, they're now just one point behind United. Solskjaer's side have nine points from eight games themselves and that simply isn't good enough.
Things won't get easier any time soon either, with the Manchester club facing Liverpool next in the Premier League.
Thankfully, that fixture comes after the international break, which gives Solskjaer and his players' plenty of time to put this latest defeat behind them.
The Longstaff brothers though, will be savouring every moment of it.News Now - Sport News