Defending Pro14 champions Leinster returned to the top of Conference A with a commanding performance against Scarlets.

British and Irish Lions prop Tadgh Furlong played 40 minutes on his first game in almost a year.

Struggling Scarlets lost a third successive league match as they remain fourth in Conference B.

The Pro14 game had been rearranged after it was postponed in December because of Covid-19.

This match went ahead despite a player from the Irish province testing positive for Covid-19. The player had already been isolating having been identified as a close contact of a positive family member and Leinster reported no positive cases following Thursday’s PCR testing.

Both sides were missing internationals before the Six Nations opening weekend, with 11 Scarlets away with the Wales squad and 16 Leinster players in the Ireland camp.

Furlong’s injury furlough ends

Furlong had been released by Ireland to play his first match in almost a year and he lasted 40 minutes on his return. The prop had not played since Ireland’s Six Nations defeat by England in February 2020 because of calf and back problems.

Scarlets also had a further 13 injured players unavailable. So in a side showing 11 starting changes from the team that lost to Cardiff Blues, fly-half Sam Costelow made his first league start since joining from Leicester.

Versatile Wales back Johnny McNicholl moved from wing to full-back and Uzair Cassiem was back at number eight for his 50th appearance after replacing the concussed Sione Kalamafoni.

Scarlets started brightly and were rewarded with an early Costelow penalty, before Leinster spurned an early try chance when a Dave Kearney pass to Max O’Reilly went astray.

The inevitable happened as a result of all the visitors’ pressure when Dan Leavy crossed after a Jack Conan burst. Byrne converted.

Scarlets responded immediately with a superb flat pass to Cassiem, who in turn produced his own delightful delivery to scrum-half Dane Blacker, with Costelow converting.

The home side’s lead proved short-lived as Leinster hooker James Tracy was driven over from a concerted lineout maul, which Byrne converted and also added a penalty.

Costelow reduced the deficit with his second penalty before the hosts conceded a penalty try, with Cassiem yellow-carded after collapsing a driving maul.

Wing Cian Kelleher scored the bonus-point try just before half-time to give ruthless Leinster a commanding 31-13 interval lead.

Captain and scrum-half Luke McGrath crossed for the fifth try in the second half before Scarlets responded with a breakaway try from scrum-half Will Homer after impressive running from Tyler Morgan.

Teenage back-rower Carwyn Tuipulotu made his Scarlets debut off the replacements’ bench before Leinster full-back O’Reilly glided through for an inspired individual effort.

Replacement David Hawkshaw completed the Leinster scoring with a seventh try that finished off a flowing move. A late yellow card for replacement Jack Dunne was followed by a stunning consolation score for Scarlets replacement Angus O’Brien.

Scarlets head coach Glenn Delaney: “Execution errors and penalties allowed them field position and territory in the first-half and gave them opportunities to score.

“We corrected a lot of that in the second-half but the damage was done. For the first 20 minutes I thought it was a pretty even game but the second quarter they showed they are a class outfit when they get to your tryline.

“Yes guys had not played for a while but that is no excuse and we have to work hard at being better.”

Leinster head coach Leo Cullen: “There was plenty of good stuff in there but there was plenty to work on as well.

“With quite a number of changes over the last couple of weeks with new guys coming in it was always going to be tough, but overall I’m very happy.

“This is a tough place to come and hasn’t always been the best hunting ground for us. I thought the guys took their opportunities well, particularly in the first half where we scored four tries.

“We did get pulled apart a few times so there’s still plenty to work on.”

Scarlets: Johnny McNicholl; Tom Prydie, Tyler Morgan, Steff Hughes (capt), Ryan Conbeer; Sam Costelow, Dane Blacker; Phil Price, Marc Jones, Javan Sebastian, Morgan Jones, Sam Lousi, Blade Thomson, Dan Davis, Uzair Cassiem.

Replacements: Taylor Davies, Kemsley Mathias, Werner Kruger, Tevita Ratuva, Carwyn Tuipulotu, Will Homer, Angus O’Brien, Paul Asquith.

Leinster: Max O’Reilly; Cian Kelleher, Liam Turner, Ciaran Frawley, Dave Kearney; Harry Byrne, Luke McGrath (capt); Peter Dooley, James Tracy, Tadhg Furlong, Ross Molony, Ryan Bair, Josh Murphy, Dan Leavy, Jack Conan.

Replacements: Sean Cronin, Ed Byrne, Tom Clarkson, Jack Dunne, Scott Fardy, Hugh O’Sullivan, David Hawkshaw, Jamie Osborne.

Referee: Mike Adamson (SRU)

Assistant referees: Craig Evans, Dan Jones (both WRU)

TMO: Jon Mason (WRU).