Leinster exacted a measure of revenge over Munster with a 21-16 victory over their rivals in the BKT United Rugby Championship.
The sides had last clashed in last season's semi-final when a late drop-goal knocked out Leinster at the same venue.
All week they had made no bones about putting things right, and after a slow and error-strewn start managed to work their way into the game and punished Munster for some sloppy play of their own.
The win, secured by tries from Jamison Gibson-Park, Dan Sheehan and Jordan Larmour, sees Leo Cullen’s move to second in the table after six rounds.
It was a thrilling and compelling derby, played out in perfect conditions in front of an almost full Lansdowne Road, that harked back to the good old days of the rivalry.
Graham Rowntree's side will be left with frustration, however, and twice late on had worked their way into the Leinster 22 only to be let down by poor breakdown management.
A crowd of 49,246 attended, most of whom were in place ahead of kick-off to applaud Johnny Sexton [below], the former Ireland and Leinster skipper, who retired following the World Cup.
And anyone who was more than six minutes late missed an early try-of-the-season contender.
Shane Daly fielded a high ball inside his own half and captain Diarmuid Barron's strong carry put Munster on the front foot.
Garry Ringrose rushed out of the line to make a trademark hit but was too easily evaded by Simon Zebo, who set off down the wing.
Calvin Nash and Antoine Frisch were in support with the centre offloading to Craig Casey, who would have been second favourite to win his one-on-one with Ross Byrne.
However, the scrum-half pushed away Byrne, who injured himself in the attempt, and dived to score.
It was a devastating moment for the Leinster out-half, who trundled past Ireland rival Jack Crowley as he nailed a touchline conversion.
Leinster could not get into the game and only a moment of white line fever prevented a second score.
Stephen Archer, on the occasion a record 269th Munster cap, was held up but the hosts were struggling to deal with the runs of Zebo, Crowley,Tadhg Beirne and Jean Kleyn, the World Cup winner making his first appearance of the season.
More pressure inside the 22 saw Leinster concede a penalty at the breakdown and Crowley put Munster 10-0 up after 14 minutes.
A scrum penalty provided the platform for man of the match Jack Conan to attack but a forward pass ended the move. It was one of a number of first-half fumbles by Leinster, who started with 15 Ireland internationals.
Hugo Keenan, James Ryan and Jimmy O'Brien couldn’t get to grips with the ball and they also mangled a five-metre lineout after Rory Scannell was yellow-carded for slowing up the ball close to the line.
It was all happening and Leinster eventually got up and running after a poor decision by Beirne to offload under pressure in midfield.
The ball bounced up for Gibson-Park, who hacked it long and outstripped the defence before applying a calm finish, his try converted by Ciarán Frawley.
It took about 25 minutes for Leinster to get to grips with the ball and when they did they were able to show what they are about.
Munster struggled to deal with the fast loop moves with Robbie Henshaw and Joe McCarthy available to carry hard when needed.
They took the lead when, after another breakdown penalty, Sheehan directed a lineout maul over the line, his score again converted by the replacement out-half.
The hosts finished the half on top but a wayward Gibson-Park pass skidded into touch on the 22 with Leinster leading by four at the break.
Munster soon gained the upper hand but two knock-ons in the opening five minutes halted their momentum.
Andrew Porter made a break in midfield but Jimmy O'Brien got turned over by Crowley, who won a jackal penalty. Gibson-Park was then spoken to by referee Chris Busby with the scrum-half twice costing Leinster 10 metres.
He soon penalised Leinster again for slowing down the ball and Crowley reduced the deficit to the minimum 11 minutes into the second half.
It was relentless stuff and Gibson-Parked tapped a quick penalty that led to a lineout inside the 22, Munster surviving after Tadhg Furlong knocked on five metres out before John Hodnett further eased the pressure by winning a jackal penalty over Keenan.
Then it was Munster’s turn to attack and Zebo almost broke the line but the move died when Conor Murray hesitated at the back of a ruck and Conan came up with the play.
From there Leinster worked their way up field and the ball was spun to Larmour, who stepped inside Daly and dipped past an injured Zebo to grab a crucial try.
Frawley, who was excellent after being pushed into action early, landed the touchline conversion, which sent Leinster two scores clear with just 12 minutes to play.
Crowley added a penalty with six minutes left and Munster almost stole the game when Murray danced down the sideline before Larmour’s cover tackle stopped the immediate danger inside the 22.
Still under pressure, Caelan Doris came up with another steal at the breakdown and despite a late siege on the Munster line, Leinster left with out a bonus point.
The derby is well and truly back.
Leinster: Hugo Keenan; Jordan Larmour, Garry Ringrose (co-capt), Robbie Henshaw, Jimmy O'Brien; Ross Byrne, Jamison Gibson-Park; Andrew Porter, Dan Sheehan, Tadhg Furlong; Joe McCarthy, James Ryan (co-capt); Jack Conan, Josh van der Flier, Caelan Doris.
Replacements: Rónan Kelleher, Jack Boyle, Michael Ala'alatoa, Ross Molony, James Culhane, Ben Murphy, Ciarán Frawley, Scott Penny
Munster: Simon Zebo; Calvin Nash, Antoine Frisch, Rory Scannell, Shane Daly; Jack Crowley, Craig Casey; Jeremy Loughman, Diarmuid Barron (capt), Stephen Archer; Jean Kleyn, Tadhg Beirne; Tom Ahern, John Hodnett, Gavin Coombes.
Replacements: Scott Buckley, Dave Kilcoyne, John Ryan, Brian Gleeson, Alex Kendellen, Conor Murray, Tony Butler, Shay McCarthy.
Referee: Chris Busby
