The top two sides in All-Ireland League Division 1B clashed at Castle Avenue on Saturday afternoon, with tries from winger Michael Keating and hooker Aaron Dundon proving crucial for Clontarf.
The north Dubliners came from 15-11 down, thanks to converted tries from Michael Keating (58 minutes) and Aaron Dundon (68), to overhaul Buccaneers and extended their lead at the top of the table to four points.
Buccs had the wind at their backs in the opening half, but fell behind to a penalty from Clontarf out-half Noel Reid. Michael Kearney, on as a replacement for former Leinster lock Ben Gissing, then broke through for an unconverted try.
Reid and Buccs’ David Connellan swapped kicks – a drop goal and penalty – as the half came to a close with Bernard Jackman’s men leading 11-3.
However, the midlanders came out a renewed force for the resumption and they dictated the pace, profiting from some improved restarts.
A yellow card for Clontarf prop and captain Niall Treston for persistent infringing, nine minutes in, invited Buccaneers on.
From a scrum, their number 9 Conor O'Loughlin sprung through a gap and set up former Ireland Under-20 winger Shane Monahan for a try on the left.
Monahan then turned provider as his kick through was gobbled up by overlapping full-back John O'Brien for a second try, which Connellan converted. Suddenly, the hosts looked in trouble.
They had a touch of good fortunate when a slip by a Buccaneers defender, following a break by flanker Ross McCauley, created the opening for Keating to notch a seven-pointer, with Reid adding the extras.
And in a fast-paced, competitive final quarter, a well-judged chip from replacement Martin Dufficy teed up Dundon for the clincher.
Referee: Leo Colgan (IRFU)