Clontarf moved back up to third place in the Division 1A table thanks to a 27-16 victory at home to Ballynahinch, however they will be frustrated that they missed out on a bonus point.
Winless in their three previous matches, Clontarf scored three first half tries through backs Michael Brown, Matt D'Arcy and Rob McGrath, the brother of Leinster winger and Castle Avenue favourite Mick McGrath.
Blindside flanker Karl Moran got the plaudits for his efforts in the build-up to Brown's opening score, taking a great line in the third minute to put the centre over beside the posts.
Out-half David Joyce converted and kicked a penalty before Ballynahinch's Chris Quinn replied with a three-pointer of his own.
D'Arcy and 'Hinch hooker Jonny Murphy then swapped tries, and the north Dubliners finished the opening half in good stead by creating an opening for right winger McGrath's touchdown to lead 24-10.
However, Andy Wood's men really should have had the bonus point in the bag by then. They wasted a number of promising attacking positions with their decision making or the absence of the final pass letting them down.
The second period was a slow-burning affair with defences on top for long spells. 'Hinch, whose set piece game improved, tightened up in defence to cut down the opportunities for the title holders whose only score came from a Joyce penalty.
Their Co. Down opponents reduced the arrears to 11 points thanks to two more penalties from Quinn's boot – 'Hinch were camped in the hosts' 22 for a 15-minute period – but 'Tarf prevented them from picking up a late losing bonus point.
The hosts had a man-of-the-match performance from workhorse number 8 Tony Ryan, who could be a key figure in their pre-Christmas trips to Young Munster and Old Belvedere.
Referee: Kieran Barry (IRFU)