Kelleher, the man-of-the-match, added two more tries at the start of the second half to complete his treble and replacements Max Deegan, Harry Byrne and Michael Milne finished off a runaway victory.

Back in Ireland just a week on from losing 38-14 to Ulster, the depleted Ospreys’ only consolation in Dublin was a late effort from Luke Morgan – which came when they were 53-0 down.

An early Lloyd Ashley offside was punished with an opening penalty from Ross Byrne, who then created winger McFadden’s try.

Rory O’Loughlin reacted quickest to a turnover, chipping over the top with Hugo Keenan first to the ball, and a penalty advantage developed before Byrne’s cross-field kick was grounded by McFadden in the right corner.

An inviting hole in the Ospreys midfield was ruthlessly exploited when Peter Dooley sent Will Connors galloping past halfway and he fed the supporting Kelleher who showed impressive pace to charge over from outside the 22. Byrne converted before some untidy errors hampered the hosts’ progress.

Ospreys were foiled by Caelan Doris’ turnover penalty and a second lineout steal of the night from Scott Fardy.

Their poor run of luck with injuries also continued as Dan Evans and Ashley both hobbled off, with new signing Ben Glynn making a brief PRO14 debut before injury struck him too.

Tomane thundered through a couple of attempted tackles to register Leinster’s third try, seven minutes before the break.

Following Byrne’s conversion, Ospreys enjoyed one of their best spells thanks to a Shaun Venter break and some late scrum pressure which, much to their annoyance, had no end product.

The visitors began the second half with two hookers on the field – Scott Otten had to come on for replacement lock Glynn – and Kelleher in brilliant form.

James Lowe chipped through and combined with Jamison Gibson-Park and Kelleher in a counter-ruck, the latter dribbling through and touching down from a few metres out.

With the bonus point secured, Leinster then used a penalty to set up a defence-splintering maul which handed Kelleher his third score.

Another maul platform led to Deegan crashing over from a snappy Gibson-Park pass. Fly-half Byrne landed both conversions to top off his 11-point contribution.

Dublin University scrum-half Rowan Osborne came on to make his senior debut for Leinster, his speedy service a feature in the build-up to Byrne’s younger brother Harry slipping out of a tackle from Sam Cross to make it 46-0.

Academy prop Milne then piled over at the end of 12 phases to crown his RDS debut with a converted try.

Ospreys finally got off the mark eight minutes from the end, as reserve scrum-half Matthew Aubrey’s break and quickly-taken lineout sent Morgan over.

The Welsh region lost replacement back rower Gareth Evans to the sin-bin for a no-arms challenge on McFadden, but avoided conceding a ninth try when Keenan’s try was ruled out for a forward pass from Deegan.