Veteran flyhalf David Humphreys slotted a 40 metre drop goal which went in off both posts, with only minutes remaining to win the game.

The Belfast side had been in charge for much of the game, but a late try by Ospreys scrumhalf Jason Spice, and conversion from Gavin Henson made the scores 17-16, and at that stage Leinster would have been crowned champions.

But Humphreys had other ideas and took his total to 14 points on the night with his late drop goal, Matt McCullough scored their only try, and that proved enough to seal the title.

Justin Harrison lifted the trophy, which will now return to Ireland after two years in Wales, in the absence of captain Simon Best who missed this crucial game after breaking his ankle in last week´s draw at Llanelli Scarlets.

The Ospreys drew first blood when Jonathan Vaughton scored inside eight minutes after second rows Alun-Wyn Jones and Lyndon Bateman combined to open space out wide for the young wing.

Humphreys hit back with a penalty before Ulster found their way over the line from close range. Justin Fitzpatrick drove to within inches of the line before McCullough leapt over to touch down.

Humphreys converted and added a penalty before half-time for a 13-10 advantage but should have extended that three times.

The 34-year-old dropped a pass with a clear field in front of him on the stroke of half-time and then missed straightforward penalties after 52 and 60 minutes which threatened to cost Ulster the title.

The second of those came with Wales forward Thomas confined to the sin bin for a professional foul after Stephen Ferris and Andrew Trimble threatened.

The Ospreys proved they would not give up their title without a fight when Lee Beech combined with scrum-half Spice to score, before Humphreys stole it at the death.