Leinster moved top of the United Rugby Championship table as Harry Byrne's three penalties earned a 9-3 win over Munster in a bruising derby contest at a rain-lashed Thomond Park.

A Jack Crowley kick cut Leinster's lead but Byrne's third penalty with the last kick of the game sealed their victory.

Leinster's win moves them three points ahead of previous leaders Glasgow.

With Tadhg Beirne and Conor Murray rested under Irish Rugby Football Union rules after featuring in all of Munster's games since their return from the World Cup and their Ireland team-mate Peter O'Mahony ruled out by injury, Leinster looked to have the stronger hand going into the contest.

Hugo Keenan, Andrew Porter, Ronan Kelleher, Joe McCarthy and Jack Conan were all selected by Leinster coach Leo Cullen with another of Ireland's World Cup contingent, hooker Dan Sheehan, named on the bench.

Gibson-Park a late withdrawal for Leinster

Ireland scrum-half Jamison Gibson-Park was a late withdrawal from the Leinster team which meant a first involvement for Luke McGrath since suffering a knee injury in the season opener against Glasgow in October.

Half-backs Crowley and Craig Casey started for Munster with prop Dave Kilcoyne and replacement Jeremy Loughman the other member of Ireland's World Cup squad named in Graham Rowntree's 23.

Leinster-bound Springboks lock RG Snyman did not feature for Munster because of his latest injury but the rumblings over his controversial move to the Dublin-based side continued unabated in the build-up to the festive interprovincial derby.

When the action did get under way, Munster suffered early blows as they lost captain Diarmuid Barron and fellow front row Kilcoyne to injury in the opening 18 minutes.

By that stage, Leinster were already 6-0 up in what was always likely to be a low-scoring contest given the slippery ball.

Barron's immediate infringement after the kick-off gifted Byrne his first-minute penalty with Porter's turnover yielding the Leinster fly-half's second successful kick in the 16th minute.

Porter's scrum battle with Munster prop Oli Jager, who was making his first start for the home side, was one of the features of the opening half, with honours even as they both won two penalties.

Leinster did waste a couple of glorious first-half opportunities, with Simon Zebo's superb tackle dispossessing McGrath as the visitors had two men inside, before the scrum-half was then short with a pass to Jordan Larmour when the Munster line seemed certain to be breached.

The second chance was butchered with Munster down to 14 men after Casey's yellow card for a tip tackle on Larmour.

With their wind at their backs, Munster produced pressure after the restart only for Crowley to surprisingly miss from a central position just outside the 22 before he did cut Leinster's lead in the 52nd minute.

Crowley's successful penalty came four minutes after Munster's highly promising lock Edwin Edogbo had been forced off with an apparent knee injury.

Munster were never able to get up a head of steam thereafter as Leinster wasted chances to extend their lead with Byrne hitting the the post from another penalty before being horribly off target from an even more kickable position.

But Leinster didn't panic as a turnover by man of the match McCarthy helped keep them in control before Ryan Baird's lineout steal snuffed out another potential Munster opening.

The final minutes were played in Munster's 22 as Loughman's yellow card in the final minute was followed by Byrne's match-closing third penalty.

Munster: Zebo; Nash, Frisch, Nankivell, Daly; Crowley, Casey; Kilcoyne, Barron (capt), Jager; Edogbo, Coombes; Ahern, Hodnett, O'Donoghue.

Replacements: Clarke, Loughman, Archer, Gleeson, Kendellen, Patterson, Butler, O'Brien.

Leinster: Keenan; Larmour, Ringrose (capt), Frawley, Russell; H Byrne, McGrath; Porter, Kelleher, Ala'alatoa; Molony, McCarthy; Deegan, Penny, Conan.

Replacements: Sheehan, E Byrne, Clarkson, Jenkins, Baird, McGrath, Turner, Connors.

Referee: A Brace (IRFU)