Paddy Jackson proveddecisibe with all the Irish side's points coming from the boot, slotting a penalty with just a couple of minutes left in a game Ospreys had led from the outset.

Nicky Smith bundled over for a try on his 50th appearance as the Welsh side looked for their fourth win of the season, eventually falling narrowly short in an enthralling encounter.

Ospreys learnt the lessons of last week's defeat to Leinster, beginning the first half in frantic fashion, opening up the hosts' back-line twice in the opening five minutes as Ben John in particular worked the angles.

The reward was to come moments later, Smith making the most of his accolade game to power over Rory Best to touch down, an apt reward for a string of encouraging phases of rugby.

Steve Tandy's side didn't let up either, with Dan Biggar converting for a 7-0 advantage as a direct approach seemed the order of the day, but their intuitive attack was met with smart defence to keep the try count to just one.

You wondered if the fast start could be maintained, as a stunned home crowd at the Kingspan Stadium watched just 12% of match action in the Ospreys half by the end of the first quarter, a game between two sides who have enjoyed positive starts to the Guinness PRO12 campaign.

But Ulster fought back, showing the character which saw them top the table in the early stages of the season, although Louis Ludik couldn't make the most of space in the corner when fumbling from Darren Cave.

Ulster were on the board soon after, however, with Jackson kicking on the half-hour mark, the last movement of the scoreboard after an intriguing first half which saw the excitement far from reflected in the 7-3 score.

And it was the hosts who kept on their momentum in the second period, Jackson needing just four minutes to cut the deficit to just one before an impressive Best - who returned to the starting XV - forced another infringement.

Jackson was not to be successful this time around, and although Les Kiss' side remained heavily on the front foot, resolute Ospreys defence dwindled the impact of heavy possession and territory for the Irish side.

Still Ulster came pouring forward, but the defence was matched in equal measure, almost stunning the home crowd with a try of their own.

A huge breakaway saw Tom Habberfield racing downfield, sliding out of touch under pressure at a valuable moment as the game was kept to just a solitary point.

Dan Biggar missed a chance to extend that lead, skewing his drop-goal attempt narrowly wide on the left side with just ten minutes to go in a breathless encounter.

And after a second half almost camped in the Ospreys half, the pressure told for Ulster. Just two minutes were left on the clock when the hosts won a penalty, with Jackson this time making no mistake having missed earlier kicks from the tee to steal a last-gasp victory.

Guinness PRO12 Final 2017 Ticket Information: Fans can save up to 20% on selected tickets, and prices start at just €30 adults and €5 child, and be booked via www.ticketmaster.ie. For further information visit http://www.pro12rugby.com/final