Teenage midfielder Matty Longstaff capped off a memorable Premier League debut for his boyhood club by netting the only goal against the Red Devils to secure maximum points for the Magpies
And Saint-Maximin, who previously tasted victory in United's impressive away win at Tottenham Hotspur in August, was equally pleased to gain three points in front of an elated St. James' Park crowd.
"I'm feeling really good!", Saint-Maximin told nufc.co.uk. "It was a very good win. We worked very, very hard and we won a great game against a great team. I can only be happy!
"I was with the team when we won against Tottenham and now we have won against Man United, which have been two big games for us so we are very happy.
"I'm really pleased to get my first Premier League win in front of the home supporters. I love the fans - that win was for them! I love to dribble and they are always pushing me on when I do so. I just want to keep working hard for them."
Following a difficult defeat to Leicester City a week ago - a heavy 5-0 loss at the King Power Stadium - Saint Maximin was delighted with the immediate response to secure three much-needed points.
Steve Bruce's side move out of the relegation zone into 16th place but the 22-year-old insists the squad must now build on their victory against Man United ahead of their Premier League trip to Chelsea after the October international break.
"It's a great reaction after last week," the Frenchman added. "Everybody was very disappointed after losing against Leicester but we talked about it and said that this cannot happen again.
"We are a good team with good players and we have to keep going and working hard. You always want to improve and play a great game against the great teams. We showed a lot of good things against Man United.
"It's a good time to win before the international break because everybody can now enjoy it a little bit before we play against Chelsea. We must make sure we keep going because we need to have good concentration and togetherness as a team to make sure we are ready for the next game."
