The midfielder became the latest academy product to be handed his chance by head coach Neil Redfearn when he started in Monday’s defeat at Molineux.
Phillips has joined homegrown quartet Sam Byram, Alex Mowatt, Lewis Cook and Charlie Taylor in making his first-team breakthrough at Elland Road.
“It was an honour, putting the white shirt on for the first team is something that I’ll treasure for the rest of my life,” Phillips said.
“It’s a lot easier when you’ve got people like Cookie, Mowatt, Chaz and Byram in there. It’s a lot easier for me to settle in.”
The 19-year-old added: “I found out on Sunday in training.
“Redders pulled me to one side and said ‘are you feeling alright?’ “I said ‘yes’ and he said ‘well you’re playing on Monday’.
“Then I told my mum and she wanted to tell everybody in the world. I told her to keep it quiet!”