Academy flyer Tommy O’Brien crossed for his first senior try as Leinster Rugby posted a 21-13 Guinness PRO14 win over a determined Ospreys side at the Gnoll.

Adding to O’Brien’s opener and a Josh Murphy effort, it was not until the 73rd minute that Cian Kelleher crossed from replacement Rowan Osborne’s pass to seal the result.

Ospreys had led 10-7 thanks to winger Luke Morgan’s try on the stroke of half-time, but with man-of-the-match Peter Dooley starring in a dominant scrum, the platform was laid for Leinster’s twelfth straight victory of the PRO14 campaign.

36-25 winners on their only previous visit to the Neath venue back in November 2003, Leinster had to absorb the early pressure from the wind-backed Ospreys. Out-half Luke Price watched his seventh-minute penalty from halfway bounce away off the left hand post.

Hugo Keenan had to react smartly to bring down the fast-breaking Hanno Dirksen just eight metres out, and a couple of poaches from James Tracy and James Lowe saw the province warm to their task. Jamison Gibson-Park followed up with a half-break to get them into Ospreys territory.

With Michael Bent getting the better of Nicky Smith at scrum time, Leinster gained further ground from the resulting maul, before a penalty advantage allowed Gibson-Park to attack the short side of a ruck. Quick hands from the scrum half, Kelleher and Scott Fardy sent the freshly-introduced Tommy O’Brien over in the right corner past Olly Cracknell.

Ciaran Frawley converted neatly from the right for a 7-0 lead, but Ospreys almost responded just after the restart.

Scott Otten gobbled up a box-kick and the supporting Kieran Williams broke Gibson-Park’s attempted tackle. Haring towards the left corner, it took a combination of Kelleher and Keenan to deny him with the ball going forward in contact as Leinster breathed a collective sigh of relief.

Price slid a kickable penalty wide in the 24th minute, and Leinster were then thwarted in their next attack in try-scoring range. It all started with a leg-pumping run from loosehead Dooley, with Kelleher duly closed down near the right touchline before Williams claimed turnover ball in a double tackle on the onrushing Lowe.

Ospreys showed a clinical edge as half-time approached, profiting from some loose Leinster play. Aled Davies gobbled up yards when breaking off a maul and his half-back partner Price landed a left-sided penalty to open the hosts’ account with 39 minutes on the clock.

It got even better for the Welsh region a few moments later, Frawley’s attempted pass to Keenan on halfway going to ground and Morgan hoovered it up, fended off Kelleher and scampered clear to touch down behind the posts. The sucker-punch score, converted by Price, raising hopes of Ospreys repeating last week’s home win over Ulster.

It was Morgan’s kicking error which gave Leinster vital territory early in the second period. Ospreys battled through a bout of scrum pressure five metres out from their own line, but they could not stop Murphy in the 48th minute, the flanker squeezing over beside the right hand post with timely support from Ross Molony and Scott Penny.

Frawley added the extras to give the visitors a 14-10 advantage, the scoreboard remaining unchanged with an overthrown lineout foiling a promising Leinster attack. Price punished Fardy and Penny for coming in at the side on the hour mark, making it a one-point game with the home crowd roaring their team on.

Dooley ripped the ball free from Gheorge Gajion to break up Ospreys momentum, although some scrappy phases saw the province’s handling errors climb into double figures. Young lock Ryan Baird announced his arrival off the bench with a lineout steal and a barnstorming 60-metre run – set up by Lowe’s short pass – that had Leinster hunting down their third try.

Kelleher was held up at the end of a free-flowing move sparked by Lowe’s clever midfield run off replacement Harry Byrne’s inviting pass. Ospreys lost Scott Parry to the sin-bin for hands in the ruck, and the following scrum saw replacement Osborne snipe to the right and set up a deserved score for Kelleher.

The winger’s fourth try of the season was expertly converted by Byrne in the increasingly wet conditions, a further scrum penalty and Byrne’s big right boot ensuring that Leo Cullen’s men closed out the match by pinning Ospreys back in their own 22.