The young midfielder, who turned 19 on Tuesday, came on in the second half of our 3-0 victory over Crystal Palace in the Carabao Cup.
On the hour mark, Gore slotted in alongside Casemiro for the remainder of the game in what he described as a ‘surreal’ feeling.
“It tops the list of birthdays, it was truly a special moment,” he told MUTV at full-time.
“I don’t think words can describe that feeling, seeing the fans, it is everything you’ve dreamed of, coming true.
“It means everything [to make your debut], growing up as a United fan [along with] my whole family, it means a lot to them and they were all here supporting me.