Lansdowne survived a late, late scare to finish as one-point 21-20 winners over Old Belvedere in a tense New Year encounter on the Aviva Stadium's back pitch.
Mike Ruddock's men were 21-15 ahead entering the final minutes and although Shane McDonald went over out wide for Belvedere's third try, fellow winger Josh Glynn missed what would have been a match-winning conversion.
Lansdowne, who had prop Peter Dooley sin-binned in the 78th minute, somehow held on to begin 2015 on a winning note, making it six league victories on the trot to move seven points clear at the top of the Division 1A table.
Despite being outscored by three tries to two, Lansdowne had a key contribution from experienced out-half Scott Deasy, whose 11-point haul included well-struck penalties in the 13th, 20th and 30th minutes.
Both first-half tries were scored from lineouts, Old Belvedere flanker Michael Oyuga breaking through in the 17th minute before a well-worked maul, just before the break, allowed Lansdowne flanker Joe O'Brien to respond.
A Josh Glynn penalty closed the gap to 16-8 before Lansdowne full-back Cian Kelleher celebrated his Ulster Bank Rising Star monthly award win with an unconverted 49th-minute try.
Back came 'Belvo, immediately profiting from the sin-binning of Lansdowne winger John Coleman on the hour mark. Barely a minute later, prop Adam Howard crashed over for Glynn to convert and reduce the arrears to six points.
Paul Cunningham's charges kept pressing and got their reward in injury-time when McDonald nabbed try number three. However, the kick proved too difficult for Glynn as frustrated 'Belvo fell to their fourth successive defeat.
Scorers: Lansdowne: Tries: Joe O'Brien, Cian Kelleher; Con: Scott Deasy; Pens: Scott Deasy 3
Old Belvedere: Try: Michael Oyuga, Adam Howard, Shane McDonald; Con: Josh Glynn; Pen: Josh Glynn.
Elsewhere, a strong start and finish helped Clontarf secure only their second try-scoring bonus point of the Ulster Bank League season as they dismissed St Mary's College 44-15 at Castle Avenue.
Outhalf David Joyce played a starring role for the defending Division 1A champions, who are back up to third in the table following this result.
The Tullamore man scored a try, kicked four conversions, including two from the touchline, and two penalties for a 19-point haul - his tally for the current campaign now stands at 101 points.
Tries from backs Michael Brown and Anthony McGivney, who profited from an initial break by Leinster's Colm O'Shea, had Clontarf leading 17-0 at half-time.
Second-from-bottom Mary's cut the deficit back to just five points after Tom O'Reilly and Ciaran Ruddock - two members of a combative front five - crossed for successive tries in the third quarter.
However, the visitors could only add three more points from the boot of Gavin Dunne as 'Tarf found an extra gear or two in the closing quarter. Prop Ivan Soroka's close range try was followed by Joyce's bonus-point score, as part of which he collect his own hack-on from halfway.
Joyce then swung over the conversion of winger Brown's second try of the night, and the sixth and final touchdown involved good hands from David Hegarty and Karl Moran pave the way for lock Tom Byrne to go over.
Scorers: Clontarf: Tries: Michael Brown 2, Anthony McGivney, Ivan Soroka, David Joyce, Tom Byrne; Cons: David Joyce 4; Pens: David Joyce 2
St Mary's College: Tries: Tom O'Reilly, Ciaran Ruddock; Con: Gavin Dunne; Pen: Gavin Dunne