The team recovered to score three goals in seven minutes - Shaq Coulthirst (2) and an own goal - to lead 5-3 with 15 minutes remaining.
Leicester hit back again to make it 5-4 with a minute remaining but Mason Bush had the last word in injury time for the final 6-4 scoreline.
"I thought it was an excellent performance," said coach Alex Inglethorpe.
"Leicester always provide one of the biggest challenges of the season but the lads were brave in their play and wanted to keep the ball and keep possession.
"It was a mental challenge for them after Leicester came back to lead 3-2 and they responded superbly."
We'll have more the thoughts from Alex later...
Spurs U18s: Granger, A McQueen, Ekong, Modeste, Barthram, Stewart, Zapata-Caicedo (McEvoy, 84), Munns, Lameiras (Bush, 59), Coulithirst, Ward.
Victor Zapata-Caicedo - pictured - struck twice to hand the lads a 2-0 lead in the first half but the Foxes turned the game on its head to lead 3-2 midway through the second half.