Lucan United became the first team this season to beat Tullamore Town.
The Senior 1B leaders scalped the Senior 1 promotion hopefuls in the Metro Cup.
Goals from Jack Carey, former Celtic youth Brandon Payne and a Marco Chindea double ensure the home side victory.
Lucan have had a good start to the season and have carried there form into the cup.
The Lucan side have quietly put a decent squad together with the likes of Peake and Crumlin legend James Lee signing.
They are now hoping to put a promotion push together, manager John Doyle explained.
“We have good competition for places this season and we have had a decent start. We have a lot of good sides in this division and I am expecting the promotion hunt to go right to the last weekend. We have the squad to be involved in race for promotion but we will still need that bit of luck a long the way that all sides need to gain promotion. Any team in this league can turn you over if your work rate is not what it should be. So we need to keep working hard and trying to improve as we go.”