Munster v Leinster, Thomond Pk, Tomorrow, KO 7.30, Live RTé2
Coach Joe Schmidt could come out of this weekend with two straight duck-eggs against the Ospreys and Munster after a 20-match unbeaten sequence.
This is a measure of how fast this game can change. One minute you can be on top of the world, the next you can be counting the cost of falling confidence.
In hindsight, the Ospreys had beaten Leinster on three of the last four occasions. They had the form and the game plan to disturb the Blues.
For all that, there was a decidedly ring-rusty approach to the way Leinster moved the ball around. The mistakes were many. The flow slowed to a trickle.
It is possible that this body-blow was exactly what Leinster needed ahead of the business end of the season. There is no better place to go to recover than Limerick.
The leaders have not lost away from Dublin since their Round One defeat to the self-same Ospreys. Against that, they have won just once at Thomond Park -- in April 2010.
The hoodoo returned when Munster simply refused to be humbled on their hallowed turf in the Magners League Grand Final last May.
It would have been too much to take for them to see Leinster complete the Heineken Cup-Magners double, something they themselves could not do in their European glory years of 2006 and 2008.
Munster have a chance to plant a seed of doubt by cutting Leinster's lead at the summit of the PRO12 to four points, maybe even three with a bonus-point win.
This would give them tremendous momentum going into their Heineken Cup quarter-final against Ulster back in Limerick next week.
However, they are struggling in the second row, where Paul O'Connell and Donnacha Ryan, their preferred pairing, are out at a time when Leinster have received the considerable boost of signing Brad Thorn and seeing their captain, Leo Cullen, make it through 80 minutes last Friday.
Leinster really need to arrest what happened against the Ospreys. They will also want to approach the Cardiff Blues in their Heineken Cup quarter-final in the best frame of mind.
There could be an advantage to be gained at half-back, where Conor Murray's absence means Tomás O'Leary (left) will have to confound the long-term downturn in his form.
All the sound reasoning in the world can never lead to a near-certain prediction, one way or the other, when these two engage. What price a draw?