The Magpies won the tie 1-0, thanks to a brilliant goal from Matty Longstaff, who made his impressive top-flight debut against the Red Devils.
The 19-year-old drilled home a low finish from outside the box to inflict more misery for Manchester United who are just two points above the bottom three and with two wins this season.
Steve Bruce has revealed what the level-headed young midfielder told him after he came off the field.
Bruce said to the Chronicle: “Typical of him, the first thing he said to me coming off was ‘Thank you’. “It’s ridiculous after what he’s just done.”
The Newcastle boss adds that Longstaff is a ‘great kid’ who works hard in training.
Longstaff, who started alongside brother Sean, could have scored in the first half as well. He hit the crossbar with a thunderous 25-yard drive.
It was also Steve Bruce’s first win over Manchester United as a manager in his long career.
The Magpies only enjoyed 31% of possession, and attempted 12 shots on goal during the game, according to BBC Sport.