OLD BELVEDERE 9 ST. MARY'S COLLEGE 20, Anglesea Road
Scorers: Old Belvedere: Pens: Eamonn Fitzgerald 3
St. Mary's College: Tries: Matt D'Arcy 2, Ronan Doherty; Con: Jonathan Sexton; Pen: Jonathan Sexton
Leinster out-half Jonathan Sexton kicked five points and Matt D'Arcy dummied and sniped his way to two tries as Mary's vaulted back into the top half of the table.
They got the ideal start when D'Arcy burst through for a third-minute try and Ronan Doherty added a second touchdown to leave Belvedere 15-6 behind at half-time.
Belvo winger Eamonn Fitzgerald had kicked two penalties and he added a third, making it seven out of seven for him over two games.
But the hosts, who included Leinster winger Simon Keogh, failed to convert a series of try-scoring chances, leaving D'Arcy to seal the issue 10 minutes from time.