Ninth-placed Bruff enjoyed an impressive 27-10 win over UCD at Kilballyowen Park after they made a splendid start.
Out-half Brian Cahill was on target with a tenth minute penalty and five minutes later flanker John Shine got in for a try which Cahill converted to make it 10-0.
Cahill's opposite number Niall Earls was on target with a UCD penalty when the home side was penalised in a ruck.
Bruff remained on top though and their bulky pack dominated all the way. This was evidenced after 29 minutes when number 8 Mike Carroll crossed for a try which Cahill again converted.
But UCD, in seventh place going into the game, battled on and were rewarded with a try by winger Tom Fletcher which Earls converted.
A penalty by Cahill moved the Limerick side into a double scores lead - 20-10 - and eight minutes from the end, Bruff clinched the win when Shine got over for his second try and again the place-kicking accuracy of Cahill was not found wanting when he landed the conversion.
Belfast Harlequins maintained their grip on top spot in Division 1B with a sound thrashing of their Ulster rivals Dungannon at Stevenson Park.
'Quins were in rampaging form, running out 44-17 winners with big Ulster forward Neil McComb helping himself to a hat-trick of tries - he now has seven for the league campaign.
Dungannon grabbed second half tries through Darren Simpson and Mark Jenkinson, but the power and pace of Adam Larkin's men proved too much with Michael Allen, Rory Scholes, Richard Lutton and Niall Annett also touching down.
At Dubarry Park, former table toppers Buccaneers were held tryless as UL Bohemians emerged as 15-9 victors. Highly-regarded prop Dave Kilcoyne and fellow front rower Brian Walsh crossed for a try apiece for Bohs.
Galwegians blew a 12-7 half-time lead as Ballymena came back at them in the second period at Crowley Park. Tries from Caolan Fitzpatrick, Alasdair Frazer, Rodger McBurney and John Andrew steered the Braidmen to a hard-fought 27-22 victory - their third on the trot.
Meanwhile, UCC gained some reward for their recent run of improving displays by overhauling Ballynahinch for a much-needed 13-12 win at the Mardyke.
Munster's Denis Hurley, who lined out at full-back, was one of the try scorers for the Cork students. The bottom side have now won two of their last five league games, closing the gap on Bruff to five points.