Leinster scored six slick tries in a thoroughly deserved victory over the Ospreys at the Gnoll.
Ospreys (9) 25
Pens: Henson (5)
Drop Goal: Connor
Leinster (7) 36
Tries: McWeeney, O'Driscoll (2), D'Arcy (2), Warner
Cons: O'Meara (3)
Gordon D'Arcy and Brian O'Driscoll, the game's outstanding performer, scored two tries apiece, with Christian Weener and John McWeeney adding the others.
The Ospreys managed to stay in touch for most of the game thanks to Gavin Henson's regular penalties, but the Irish visitors were well clear by the time Huw Bennett scored a late consolation try.
The home side took the lead against the run of play with a Shaun Connor drop-goal, but Leinster replied four minutes later thanks to O'Driscoll's magic.
A well timed switch move sent him bursting through the Ospreys defence, and his pace won the race for his perfectly weighted chip-kick over the last man.
Television replays raised doubts over whether O'Driscoll had applied the necessary pressure on to the ball, but referee David Changleng was happy the centre's out-stretched hand did ground the ball.
Scrum-half Brian O'Meara converted, having earlier missed an easier penalty attempt.
The Ospreys dominated for the majority of the remaining 20 minutes of the first-half, but could not quite find the final break or pass to score a try.
They came closest on the half hour mark when Leinster hooker Shane Byrne's desperate lunge denied narrowly beat Ospreys lock Andy Newman to the loose ball over the tryline.
Full-back Henson was on top form with the boot, though, and two penalties gave the Ospreys a 9-7 lead at the interval.
Leinster found the perfect reply to the second half with two tries in the opening 10 minutes.
The first came after a sweeping move from right to left released was finished off by wing D'Arcy, again converted by O'Meara.
The Ospreys failed to capitalise on Shane Williams' breaks
Henson took the Ospreys a point clear at 15-14 with two penalties six minutes later, but Leinster hit back immediately when replacement Warner broke through some weak tackling to score in the left corner.
Another Henson penalty again kept his side in touch, but the tires had given the Irishmen the confidence to open the game up and it was no surprise when a fourth try arrived.
Weak tackling was again the home side's downfall as wing McWeeney found little residence in his charge to the line to guarantee at least a bonus point.
The home defence was again found wanting minutes later when O'Driscoll broke Scott Gibbs' tackle and had enough pace to score under the posts.
O'Meara's conversion took the score to 18-31 and put his side in a strong position with 15 minutes to play.
That was to turned into a unassailable position two minutes later when Darcy scored his second and Leinster's sixth try of the night.
Ospreys hooker Bennett scored a last minute try, converted by Henson, to give the scoreline a air of respectability the home side hardly deserved.
Ospreys: Gavin Henson; Gareth Morris, James Storey, Dave Tiueti, Shane Williams; Shaun Connor, Andy Williams; Paul James, Huw Bennett, Adam Jones, Andy Newman, Gareth Llewellyn, Jon Thomas, Steve Tandy, Nathan Bonner-Evans.
Replacements: Adrian Durston, Scott Gibbs, Elvis Seveali'i, Andrew Millward, Chris Wells, Luke Tait, Gavin Thomas.
Leinster: Girvan Dempsey; John McWeeney, Brian O'Driscoll, David Quinlan, Gordon D'Arcy; Felipe Contepomi, Brian O'Meara; Reggie Corrigan, Shane Byrne, Peter Coyle, Malcolm O'Kelly, Ben Gissing, Eric Miller, Keith Gleeson, Victor Costello.
Replacements: Darren Molloy, Gavin Hickie, Aidan Kearney, Niall Breslin, Brian O'Riordan,
Christian Warner, Brown.
Referee: David Changleng (Scotland)