Longstaff, however, admits he was disappointed with the result.
"I had a lot of my mates texting me saying, 'you're so lucky to be able to do this tonight', and when you hear them say that, it makes it set in how special it is. I'm delighted to make my debut, but it's not the result we wanted," he told NUFCtv.
"But it was brilliant for me to be able to play in a game that I've always wanted to play in as a young lad, and to be able to walk out in front of the fans and see it was full behind the goal – even though it's a Carabao Cup game, there was 2,500 of them, it's unbelievable. For me, it's a brilliant night, but it was a bittersweet ending."