Leinster have built up an aura of invincibility in the Guinness PRO14 in recent seasons, especially with defeats being a rare occurrence, but they will be wary of their opponents in Saturday's final, Munster, who warmed up for their title challenge with a comfortable home win over Benetton.
Leinster may have been under-strength when they played the Ospreys in their final round-robin match, but the fact that they were beaten at home will boost the confidence in Johann van Graan’s Munster camp.
It was a late Josh Thomas charge-down try that clinched the Ospreys the dramatic five-point win over the Irish giants at the RDS arena after Leinster had enjoyed a comfortable 19-3 lead heading into the final quarter.
A man in the bin at the end for the home team, however, saw the Welshmen storm back with tries by Olly Cracknell (68th minute) and Owen Watkin (71st minute) before Thomas scored the winner.
The defeat marked Leinster’s second of the Guinness PRO14 season, with the other being earlier in the competition when they were shocked by Connacht.
They managed to bounce back strongly the following week, and will be hoping history repeats itself as they go in search of yet another title.
With the finalists having booked their place in Saturday’s season finale some time ago, the real business of the final round was Champions Cup places for next season, and it proved to be a dramatic few days on that front.
The Scarlets and Cardiff Blues went into their matches on Monday night with just three points separating them on the Conference B table, and with the top three in each conference qualify for the Champions Cup, the Scarlets found themselves deep in the mire when they fell 21 points behind Connacht in Llanelli.
They accomplished their objective with a stirring comeback, which proved handy as Cardiff - who also had to fight back from a deficit - succeeded with their part of the mission by scoring a bonus point win over Edinburgh.
The Scottish side had an outside chance of claiming a top three finish themselves and would have felt their slim hopes were still alive when they led 10-3 at halftime - an advantage that should have been bigger given the way in which they dominated the first half.
Cardiff, however, stormed back in the second period and took complete control of the game to eventually run out winners by a comfortable 19 points.
The Ospreys' win over Leinster put them out of sight of the fourth-placed Glasgow Warriors in Conference A, with the Warriors, who had a game in hand, then going on to lose without a bonus point against the Dragons.
Leinster, Ulster and the Ospreys qualified for the Champions Cup from Conference A, while the top three finishers in Conference B were Munster, Connacht and Scarlets.
Munster 31 - 17 Benetton
Leinster 19 - 24 Ospreys
Ulster 49 - 3 Zebre
Dragons 26 - 17 Glasgow Warriors
Cardiff Blues 34 - 15 Edinburgh
Scarlets 41 - 36 Connacht
Final - Saturday 27 March:
19h00: Leinster v Munster (Dublin)