Earlier Maguire had opened the scoring after 16 minutes of the opening half when he latched onto a through ball, raced clear and calmly lobbed the ball over the advancing Gretna keeper Lowson.
But Gretna bounced back to shock their more favoured opponents immediately, Davison stroking the ball home from 12 yards. with a quick fire double to turn the initiative in favour of the home side. And worse was to follow for the young Dons when White headed Gretna in front on 21 minutes from a corner.
That was how it stood until midway through the second period when Michael Paton equalised to send the game into the additional half hour. The promising young striker found time and space on the edge of the box and curled a low shot into bottom left-hand corner.
Penalties looked on the cards until, with nine minutes of the second half remaining, Maguire showed exactly why he is so highly rated with a wonder goal fit to win any game. He was just in the Gretna half and hit an incredible shot that flew in over the keeper.
It is the second year in a row the U19s have reached the semi finals of the prestigious tournament.