THE champions have lost back-to-back matches against Northampton Saints and Edinburgh for the first time since they went the same way, home and away, against Clermont Auvergne in the Heineken Cup last season.
Leinster v Ulster The RDS, tomorrow 7.15 (live RTE 2)
But they compounded that issue last season, making it three-and-out by getting trampled on by Ulster in the PRO12 at Ravenhill.
It would seem the fickle finger of fate could be drawing Leinster towards a repeat offence as they contemplate the meaning of Christmas time at the RDS. They have known the pain of defeat just once there in the league since Osprey Shane Williams twisted the knife in the Grand Final back in May of 2012.
Mark Anscombe's Ulster were the culprits last March, imposing their special brand of pragmatism for a two tries-to-none 22-18 win.
It ranks as Leinster's only home loss to a fellow Irish province since 2008, not a bad return. But the illegality of Nick Williams had them seething at the refereeing of George Clancy that night.
Ulster limited them to six penalties from Ian Madigan as speed off the line defensively and physicality in contact upset the Blues' rhythm.
The northern province could do worse than take a look back at their aggression at the breakdown that evening as the template for reducing the speed of Leinster's ball.
Ulster are the only club in Europe who have negotiated the first four rounds of the Heineken Cup without a loss on their record.
Where they were foot-perfect from week one last season, they have taken time to come together this term. It may just make for a better equation in the long run.
They have lost two of their first three in the PRO12, winning six of their last seven to sit in second, six points behind Munster, one ahead of their hosts.
Leinster won't have to be reminded that Ulster completed the double over them last season. That did not go down too well. This could be payback time.