Celtic Cup: The final scoreline perhaps doesn't accurately reflect such a fluctuating contest that still only had a score in it with five minutes to go. Nevertheless, after living on their nerves, Leinster kept their heads to play their way out of trouble and deservedly record their first competitive win of the Gary Ella reign.
In so doing they advanced to the quarter-finals of the Celtic Cup yet the competition's first tie on Irish soil also underlined how times have changed in the Celtic corner of the rugby world amid the World Cup.
The Welsh visitors recovered from a 21-3 deficit to get within three points just after the hour.However they resorted to all manner of spoiling to cynically deny Leinster momentum at key moments and over the night the home side gave a disappointingly small crowd of about 3,000 more to cheer about.
In a fine back row, Aidan McCullen skilfully led from the front, Des Dillon ran like an American running back and Shane Jennings came up with some big plays. Aidan Kearney had a big game out of touch and Brian O'Riordan, though his pass continues to need work, undoubtedly gave Leinster's attacking game another edge from the base while Gordon D'Arcy played confidently and John McWeeney's improvement was striking.
While the greater emphasis on off-loading in the tackle needs fine tuning, some of the old virtues remain and the Leinster lineout provided a solid platform to work off, laying the foundations for Leinster's first-quarter 14-0 lead. From a 20-metre rumble by the pack off a take by Kearney, outhalf Matt Leek drifted outside Shaun Connor to score and add the conversion himself.
After his travail against Munster, Leek's confidence soared and with O'Riordan enjoying an all-too-rare start behind, Leinster played much of the first half on the front foot.
They were rewarded again with a sharp break by O'Riordan off another Kearney take and good handling by McCullen, Leek, Kieran Lewis and D'Arcy to give McWeeney the chance to score wide out.
Leek again converted and despite a Gavin Henson penalty, the Ospreys' wings were clipped further when Lyndon Bateman was sinbinned after nearly beheading a jinking D'Arcy, though somewhat harshly given the Leinster full back is about half the lock's size and was dipping a little on impact.
From the resultant penalty to touch and another Kearney take, Leek again glided through a distracted defence to find the supporting Chris Warner; Dillon then pirhouetting and holding on to O'Riordan's quick long pass off the recycle to score.
Against that a couple of long-range penalties for Henson - especially the questionable view of touch-judge Marshal Kilgore that Leek had tripped the full back late rather than a genuine tangle of legs - allowed the Ospreys to troop off for the break still in the game at 21-9.
They were right back in it when flankers Steve Tandy and Gavin Thomas made some hard yards off a line and good straight running and handling along the line put Elvis Sevalai'i over in the corner. Leinster were living a little off scraps, Shane Jennings's big gallop and good work by the pack putting Leek into smartly taken, drop-goal territory.
However, the Ospreys were stretching Leinster to breaking point, good tackles by Warner and D'Arcy on either touchline stemming the tide until Henson was worked into the corner in similar fashion to the previous score - the key being Scott Gibbs's skilful support turn and offload to keep the move going at speed. Suddenly the Ospreys were sniffing some unlikely prey.
Leinster's response was telling, a sustained drive culminating in D'Arcy pumping his legs close to the Ospreys' line and when Tandy blatantly came around to prevent any chance of a sevenpointer, he was binned and Leek made it 27-21. It still needed more big plays, O'Riordan's try-saving blindside tackle to force Thomas into the corner flag, a Kearney lineout steal, O'Riordan's big touch find, some more rumbling by each of the back row, D'Arcy and Warner for another Leek penalty.
Warner had the final say with a one-handed intercept of Gibb's blindside offload and skilful juggle before making all of 80 metres along the touchline.
SCORING SEQUENCE: 7 mins: Leek try and con, 7-0; 21 mins: McWeeney try, Leek con. 14-0; 23 mins: Henson pen, 14-3; 34 mins: Dillon try, Leek con, 21-3; 37 mins: Henson pen, 21-6; 40 mins: Henson pen, 21-9; Half-time: 21-9; 43 mins: Sevalai'I try, 21-14; 49 mins: Leek drop goal, 24-14; 61 mins: Henson try and con, 24-21; 68 mins: Leek pen, 27-21; 77 mins: Leek pen, 30-21; 78 mins: Warner try, 35-21.
LEINSTER: G D'Arcy; J McWeeney, K Lewis, C Warner, B Burke; M Leek, B O'Riordan; J Lyne, G Hickie, E Byrne, A Kearney, B Gissing, A McCullen, S Jennings, D Dillon. Replacements: D Blaney for Hickie (35-40 mins, and 60 mins), D Quinlan for Lewis (50 mins), G Browne for D'Arcy (77 mins), N Breslin for Kearney (80 mins).
NEATH/SWANSEA OSPREYS: G Henson; D Tiueti, J Storey, S Gibbs, E Sevalai'i; S Connor, A Williams; P James, C Wells, A Millward, A Newman, L Bateman, G Thomas, N Bonner-Evans, S Tandy. Replacements: L Tait for Basteman (53 mins), B Williams for Wells (66 mins), J Bater for Tandy (77 mins), C Griffiths for James (80 mins).
Referee: David Changleng (Scotland).