Leinster ended the Ospreys play-off hopes with a bonus point win at the RDS, but it was a valiant effort from the defending champions who refused to surrender their crown without a fight.
Leinster led from early on, racing into a 14 point lead within 25 points before the Ospreys rallied, tried from Dan Biggar and Ben John bringing them back to within five at the break. However, after the interval Leinster once again built up a health 15 point lead and although a late rally saw Tom Isaacs touch down there was too much ground for the Ospreys to make up.
The defeat was made even harder to take by the scoreline coming in from Parc Y Scarlets, where the hosts were thumped 41-17 by Treviso, meaning any kind of Ospreys win would have taken the region into the play-offs once again.
As expected it was a fast and furious opening, with the forward battle physical and both teams looking to move the ball through the hands at every opportunity.
It was the visitors who had the chance to draw first blood after Leinster were penalised close to the left hand touchline inside their own 22 five minutes in but Dan Biggar was unable to deal with the swirling Dublin wind as he put his kick wide of the sticks.
Within two minutes the Ospreys players found themselves back under their posts as Leinster struck, scoring a try that had more than a touch of fortune about it. Fergus McFadden's kick through up the right appeared to deflect off Richard Fussell's boot, the spin and bounce catching out former Leinster U18 Ross Jones, the youngster failing to deal with it, allowing Andrew Conway to hack forward before winning the footrace to score. Jonathan Sexton's conversion left the hosts seven points ahead with the same number of minutes on the clock.
The Ospreys were forced into a reshuffle on the quarter hour mark, Rhys Webb forced off with a knee injury which meant Tom Habberfield moved to scrum half with Jonathan Spratt coming on in the centre, Ben John shifting out to the wing.
Despite the two early setbacks the Ospreys continued to take the game to their opponents, showing plenty of spirit, but Leinster's grip on the game was tightening and it came as no surprise when they doubled their lead eight minutes later.
Isa Nacewa's kick to the corner forced Biggar to concede a line out deep inside the Ospreys 22 and a combination of quick lineout ball and weak tackling allowed Luke McGrath to burst forward before offloading to Conway for a simple run-in for his, and Leinster's, second try. Sexton converted.
To the Ospreys credit they came straight back at Leinster, Biggar putting them close to the opposition line. Somehow the Ospreys snaffled the ball off a Leinster throw at the lineout and after Alun Wyn Jones and John had been halted just short Biggar's little dink through to the corner had just too much on it for Joe Bearman out wide.
Leinster were immediately guilty of playing themselves into trouble unnecessarily as Ian Madigan looked to get the game restarted quickly from the 22, somehow knocking on and allowing the Ospreys to keep the pressure on. With first a knock-on advantage, and then a penalty advantage they inched towards the line, and after another Leinster offence just metres out, Biggar's quick thinking saw him tap and go, eventually being driven over by Sam Lewis and Spratt to score. The fly-half picked himself up to convert his own try, cutting the deficit to seven with just 10 to go until the break.
The Ospreys spirit was shining through as they kept up the pressure, adding a second try just five minutes later through John. Ross Jones was the catalyst, a scything run through the middle of the Leinster defence eventually halted just a few metres short. It was recycled quickly and spun wide to the right where Bearman drew the tackle before providing the scoring pass for the Loughor product who stretched over to touchdown in the corner. Biggar was unable to add the extras which meant the Ospreys trailed by two.
The heavens opened as the clock-struck 40, but the elements didn't prevent Sexton slotting over a 40m penalty to put some daylight between the teams at the break.
HALF-TIME: LEINSTER 17 OSPREYS 12
With the Scarlets trailing at the interval the Ospreys knew that they still had a chance, no matter how slim, so the message from the coaches would have been to keep it tight, but as with the first half, they had the worst possible start to the second period, going further behind inside three minutes of the restart.
Once again the scorer was right wing Conway, who kicked ahead from halfway and then beat Ross Jones to the ball, the bounce again doing for the Ospreys youngster. Sexton's conversion went in off the far stick, meaning the visitors were 12 behind.
It remained an enthralling contest, Leinster looking to pin back the Ospreys at every opportunity, while the visitors were looking to run from anywhere, looking to claw their way back into the game.
Sexton struck what looked to be the decisive blow on 55 minutes with a kick from wide out on the left after Nigel Owens ruled that the Ospreys were guilty of bringing down the scrum, the kick taking Leinster more than two converted tries clear.
As we moved into the final quarter Biggar ignored the easiest of three points, right in front of the posts after a Leinster offside, going to the corner instead. Leinster were able to repel the Ospreys lineout maul, but they stayed pinned back in their corner, a series of scrums eating up the clock. Eventually the Ospreys pressure seemed to tell, Ashley Beck taking Biggar's pass and going over the line to ground only for the pass to be ruled forward, allowing Leinster to clear from the resulting scrum.
Back came the Ospreys, refusing to give up the fight, Fussell's running taking them back into the danger area. Biggar's leg drive saw him carry close to the line and then skipper Alun Wyn Jones was driven agonisingly close. He lost the ball over the line, only for a Leinster knock-on to result in another Ospreys scrum five.
This time, with a penalty advantage in their favour after a Leinster offence on the line, with defenders sucked in Tom Isaacs was in acres of space on the left and Biggar's looping miss pass gave him the simplest of scores. Biggar's conversion brought the Ospreys back to within eight points and with just eight minutes remaining.
For a moment thoughts went back to last May and the incredible win at the same ground in the PRO12 final when the Ospreys overturned a nine point deficit in the last 10 minutes, but just as the noisy travelling Ospreys support started believing in the impossible then back came Leinster to dash their hopes.
A Sexton penalty pulled Leinster away from the Ospreys and then at the death Cian Healey managed a breakway score to seal the win, Madigan converting.