The Monaghan Harps player tragically lost his life in a car accident.
The Farney face Armagh in the Ulster Championship semi-final, but took the time beforehand to give a moments round of applause, in memory of the the 19-year-old.
Brendán Óg Duffy was on his way back from captaining the Monaghan u20 side in their Ulster semi-final against Donegal, when he was involved in a fatal car accident.
The senior squad also wore black bands around their arms, to show respect and solidarity to the family of their young teammate.
Armagh and every spectator from both sides were unanimous in their respect, joining in on the round of applause, as every Gael in the country carries a heavy heart with them today.