Muto had failed to find the back of the net in his first six Premier League games for Newcastle following his summer arrival from Mainz.
However, the Japan international opened his account at Old Trafford on Saturday when he put his side 2-0 up after just 10 minutes before Jose Mourinho’s side came back to win 3-2.
Muto has seen the positives in the performance, though, and revealed that he was desperate to score as he started for the first time this season.
"I would like to build my future from the goal at Man United,” said Muto in the Evening Chronicle.
He added: "If I had missed this chance (to start), I couldn’t see when the next chance could come.
"So, I was really focused on grabbing a good result.
"I was confident that I could start then my motivation would be sky high because we were against very strong opponents.
"As a result, scoring a goal against them has given me more confidence."
Despite his goal against United, he could not help but feel he could have done more to earn three points as he missed a golden opportunity to make it 3-0.
"I should have scored another goal with a chance like that,” he said. "That was the worst possible result for us. But we have to stay focused on the future."
Newcastle now have just two points from their opening eight games and will be looking to improve their form after the international break.
Muto started for the first time against United and his manager Rafa Benitez was impressed with how he played alongside Ayoze Perez
"“I think it was important for us to have some mobility and pace in attack, and his understanding with Ayoze (Perez) was quite good,” said Benitez.