Guinness PRO12 leaders Ulster left it late to beat Ospreys as Paddy Jackson’s 79th-minute penalty secured the hosts a 9-7 victory.

The visitors had not trailed until Jackson slotted over his third penalty of the game to continue his side’s 100% start to the league campaign.

The home side’s last-gasp win meant the Ospreys – who scored the game’s only try early on from prop Nicky Smith – fell to their second straight league defeat.

Even though they took four vital points, this was a misfiring effort from Ulster who trailed 7-3 at half-time after Smith’s try had been converted by Dan Biggar, who missed a second-half drop-goal attempt.

Ulster had to deal with the withdrawal of Iain Henderson prior to kick-off with an injured elbow, with Robbie Diack coming into the starting line-up.

The visitors scored in the fifth minute when Smith barrelled over from close range after a clever kick from Dan Evans had forced Ulster to concede a lineout near their line.

Biggar converted and the Ospreys had thrown down the gauntlet to their hosts.

Ulster were shaken but gradually worked their way back into the game only for Jackson’s 24th minute penalty attempt to sail wide.

The home side stayed in Ospreys’ territory and a sweeping move going left saw Charles Piutau link with Louis Ludik with the South African’s pass to Darren Cave being too difficult for the centre to hold.

Still, Ulster managed to come away with their first points when Jackson landed a 28th-minute penalty after Ben John was penalised for not rolling away but that was as good as it got for the home side in the first half.

On the resumption, Ulster needed a quick response and got one after Josh Matavesi’s high tackle on Ludik just four minutes in with Jackson making no mistake and narrowing Ospreys’ lead to one point.

They then had a golden chance to take the lead in the 49th minute only for Jackson to again hit the attempt wide.

Despite Ulster trying to turn the screw in Ospreys’ half, they got nowhere and only a last-ditch tackle from Jared Payne prevented Eli Walker from scoring a break-out try in the 65th minute.

Five minutes later Ulster breathed a sigh of relief after Biggar’s drop goal went wide, and it took another last-ditch hit, this time from Ludik, to haul down Tom Habberfield short of making the right corner soon after.

It looked like they could not possibly salvage a result but the in the closing minutes Cracknell was penalised – it seemed harshly – for not rolling away and Jackson put Ulster in front.