Guiseley lead 1-0 at half time following a keenly contested start to the game.
But the young Farsley lads stepped up a gear in the second half, with goals from Bubba Krubally, Tom Priestley-Standing and Aiden Hawkridge giving the Celts the win.
ETS lead coach Luke Dean praised the team’s performance. He said: “It was an even first half, we had our chances but we didn’t finish. I felt we dominated the second half and we showed a lot of character to come back.”