Leinster Rugby’s defence stood tall as their dogged 13-6 Guinness PRO14 derby win over Munster extended their unbeaten run in this year’s competition to nine games.

Leo Cullen’s men repeated their St. Stephen’s Day 2017 victory in Limerick, using a very strong first-half wind to pick up crucial points – including an early Ed Byrne try – and then defend stoutly during a typically tense finale.

The visitors led 13-3 at the break, aided by eight points from Ross Byrne’s right boot, and although JJ Hanrahan’s penalty brace cut the gap to seven, Munster misfired most notably from a couple of late lineout opportunities.

‘The bit of dig-in for each other’ was what pleased Cullen most in the end, with 23-year-old scrum half Rowan Osborne impressing on his first start – he replaced an ill Jamison Gibson-Park – and No 8 Caelan Doris in man-of-the-match form.

Munster’s eagerness for a strong start was punctured by loosehead Byrne’s ninth-minute touchdown. James Lowe’s incisive run did the initial damage, and after Jimmy O’Brien and Andrew Porter were stopped short, Byrne managed to burrow over.

Ross Byrne converted and then tagged on a 22nd-minute penalty, punishing Chris Cloete’s breakdown offence. Osborne, Byrne’s busy half-back partner, was standing up well to the Thomond Park pressure.

Territory-starved Munster were boosted by Jack O’Donoghue’s maul defence and a subsequent scrum penalty. However, a lineout infringement by the Waterford man allowed Byrne to put 13 points between the sides.

It was back to 10 after Hanrahan rewarded a late Munster surge, which came from a Nick McCarthy charge-down and another scrum penalty. The Munster out-half doubled his contribution after a spritely start to the second half.

While Leinster showed impressive ball retention, Munster were finding joy through the direct route. Rory Scannell’s booming touchfinder and the 56th-minute entry of the returning Joey Carbery raised the decibel level significantly.

It was tit-for-tat past the hour mark, replacement hooker Sean Cronin’s turnover penalty being followed by an O’Donoghue-led choke tackle on Doris.

Munster built momentum through their forward carries, but a promising lineout maul near the right corner was grounded and Scott Fardy, Leinster’s captain for the night, soon swooped in for a turnover penalty.

Having leaked six tries to Ulster last week, the Leinster coaches were visibly pleased to keep Munster try-less. Their desire to extend their winning streak this season to 13 games was summed up by a bone-crunching double tackle by Will Connors and Cronin on Darren O’Shea.