BLACKROCK COLLEGE 9 ST. MARY'S COLLEGE 26, Stradbrook
Scorers: Blackrock College: Pens: Darragh Fitzpatrick 3
St. Mary's College: Tries: Ronan Doherty, Darragh Fanning, Robin Copeland; Con: Gavin Dunne; Pens; Gavin Dunne 3
St. Mary's dominance in the scrum, where the formidable trio of Jack McGrath, Richie Sweeney and Rob Sweeney excelled, helped them complete a league double over a Blackrock side that was missing the spark of young guns Andrew Conway and Brendan Macken.
Indeed, there were uncontested scrums at Stradbrook in the closing stages, with injuries robbing 'Rock of their supply of front rowers.
St. Mary's had the better of the opening half but failed to put their chances away, and three penalties from full-back Darragh Fitzpatrick had the home side 9-8 ahead at the break.
The visitors' early points came from a Ronan Doherty try and a Gavin Dunne penalty. Winger Doherty showed a clean pair of heels to the Blackrock cover as he shifted onto the outside and darted over for an eighth minute score.
Scoring chances were few and far between as defences dominated up to the interval, and it took a second successful kick from full-back Dunne to edged St. Mary's ahead, just after the restart.
Peter Smyth's men did not look back and well-taken tries from lock Robin Copeland and winger Darragh Fanning, with Dunne adding one conversion, saw them stretch into a 17-point lead.
Copeland's ninth try of the league campaign - he remains the division's top scorer - came after some good build-up play from flanker Paul Nash and Doherty.
Blackrock's hopes were hit when their scrum half David Moore was sin-binned for a high tackle, and Copeland turned provider for the visitors' third try late on when his good hands sent Fanning diving over.
With the St. Mary's defence proving water-tight, 'Rock could find no way back and this result leaves them third-from-bottom and with work still to do if they are to keep ahead of relegation-threatened Clontarf.
BLACKROCK COLLEGE: Darragh Fitzpatrick; Stanley McDowell, Kyle Tonetti, Rob Keogh, Shane Monahan; James Power, David Moore; Jonathan Barretto, Cian Culleton, Arthur Lyons, Des Dillon (capt), Paul Huntly, Paul Ryan, Zack Farivarz, Mick Carroll.
Replacements: Tony O'Kane, James Mannion, Paul Graham, Alan Henry.
ST. MARY'S COLLEGE: Gavin Dunne; Ronan Doherty, Stephen Grissing, Mark Sexton, Darragh Fanning; Shaun McCarthy, Conor McPhillips; Jack McGrath, Richie Sweeney, Rob Sweeney, Gareth Logan, Robin Copeland, Damian Hall, Paul Nash, Hugh Hogan (capt).
Replacements: Colm McMahon, David Kilbride, Barry O'Flanagan, Steve Bradshaw, Stuart O'Flanagan.
Referee: John Lacey (IRFU)