THE GAA club of Dubs star Barry Cahill went on fire shortly after the Blue's semi-final victory on Sunday.
Gardai are now investigating the blaze which gutted a dressing room at the back of St Brigid's GAA clubhouse in Blanchardstown.
A number of units of Dublin Fire Brigade attended the scene in response to a 999 call.
"There were 30 or 40 people in the bar at the front of the building when the fire broke out," a source said.
"The dressing room where the blaze broke out is actually in the back of the same building.
"It appears that a fire was set, which gutted the dressing room and a fair amount of training gear that was being kept in there."
The cost of damage to the dressing room and training gear is believed to run into thousands of euro.
It is believed CCTV footage may help to shed more light on how the fire was started.
Anyone with information is asked to contact Blanchardstown Garda Station on 01 666 7000.