A second half revival from Clontarf against Garryowen saw the table-toppers maintain their advantage at the top of the AIB League Division One.
Ballymena made the win all the sweeter when they were beaten by an identical scoreline of 21-15 at Templeville Road by St Mary's.
Third placed Lansdowne were not as accommodating however as they disposed of Carlow by 48 points to 22.
Buccaneers made their long trip north worthwhile with a 25-17 win over Belfast Harlequins.
Cork Con came out on top in titanic tussle with Blackrock College, winning 37-33, denying Rock the chance to make up ground on Ballymena.
Dungannon added yet more misery to Terenure's poor season, winning 45-12.
Galwegians jump into sixth place with a 20-6 win over UCD, while Shannon defeated UL Bohemians by 33 points to 16.