Leinster swapped places with Provincial rivals, Munster, to lead the RaboDirect PRO12 table after both teams were involved in pusating contests on Saturday night.
Munster suffered an 18-13 defeat to Scarlets in Llanelli, the Welsh side turning over a 13-8 deficit at the break to take the win which puts them back in contention for the play-offs.
Meanwhile, in Dublin, Leinster faced Glasgow Warriors in a crunch game with the Scots looking to pick up from losing to the Dragons the previous week and keep their play-off hopes on track.
But in an absorbing six try contest, Leinster took the spoils 25-23 and in doing so the defending champions moved to the top of the table, a point ahead of Munster.
Ian Madigan converted Rhys Ruddock’s 63rd-minute try and kicked 13 points in all as Matt O’Connor’s men took advantage of leaders Munster’s defeat at the Scarlets.
Returning to the RDS, where they lost to Leinster in last year’s semi-finals, Glasgow gave their all in pursuit of only their second victory in 18 visits to Dublin.
Madigan accumulated 11 points and Noel Reid and man-of-the-match Darragh Fanning broke through for tries as Leinster took a 21-15 lead into half-time.
Glasgow showed their attacking capabilities, with two Richie Vernon tries and an injury-time penalty from Finn Russell making it a six-point difference.
Niko Matawalu burrowed over from a ruck for the Warriors’ third try with Russell’s conversion putting them a point clear after 51 minutes.
But Leinster’s pack eventually broke the Scots’ resistance, flanker Ruddock muscling over for the decisive seven-pointer on a wet night in the Irish capital.
Meanwhile, in Llanelli, Scarlets held on to claim an 18-13 victory over Munster, who were denied an unprecedented clean sweep of victories over the four Welsh regions.
The Munstermen had to settle for a losing bonus point which stretched their lead to three points over Leinster.
A try apiece from scrum-half Gareth Davies and flanker John Barclay were the back bone of the victory at Parc y Scarlets with Munster’s only try coming from wing Gerhard van den Heever.
The match saw British & Irish Lions centre Jonathan Davies return for the Scarlets giving him an opportunity to prove his fitness ahead of Wales’ RBS 6 Nations clash with England at Twickenham next Sunday.
Davies was back after recovering from a pectoral injury in Wales’ defeat to South Africa last November. He partnered former England international Olly Barkley in midfield.
Leaders Munster, who had won all their previous seven games against the four regions, made eight changes from the side that beat the Ospreys last weekend.
Elsewhere, Zebre completed their first league double over a club in the competition when they won 15-10 in Parma against Cardiff Blues.
The Welsh side had a try controversially disallowed in the last minute.
Connacht romped to a 38-6 win over Treviso in Glaway.