The Ospreys may have scored the only try of the match through Jerry Collins but five penalties from man of the match Jonathan Sexton and an ugly drop goal by Isa Nacewa saw the Irish side win without having to hit top gear.
Even with five British Lions in their squad, the Ospreys looked bereft of ideas as Leinster were more then happy to soak up what the home side had to throw at them.
Sexton got the scoring moving as early as the fourth minute with his first penalty with James Hook cancelling that out three minutes later. Sexton then regained the lead in the 15th minute with his second effort.
Leinster went through the phases to put the Ospreys under pressure but the home side kept their try-line intact before taking the game to the European champions.
The forwards took it upon themselves to show the backs how to score in the 25th minute. Former All Black backrower Jerry Collins was at the heart of the action, taking the ball into a maul and then with the assistance of Ian Gough, powered his way over to score his second try in three games for the region.
Sexton had a chance to immediately regain the lead for the Irish side but he missed a difficult penalty from the sideline and he then miscued with a simpler effort a few moments later. The Leinster fly half then made a scything break and with Shane Jennings unmarked he elected to go on his own and was tackled and the move was killed stone dead.
The home side were reduced to 14 men when Collins punched Sean O’Brien five metres from the Ospreys try-line. Things then got worse when loosehead prop Duncan Jones was sent to the sin bin for consistently infringing in the scrum. Somehow the referee didn’t deem it worthy of a penalty try. Under immense pressure the six-man Ospreys scrum then turned the screw and earned themselves a penalty to survive the bombardment.
Looking to hold out Leinster the Ospreys gifted the visitors three points when Andrew Bishop was caught in front of the kicker. Sexton banged over the penalty to give Leinster an 8-9 lead two minutes after the break. From the restart Leinster were penalised for blocking and with the aid of an upright Hook restored the Ospreys lead with a penalty.
The Ospreys then put themselves under pressure when basic mistakes saw Leinster surge downfield and Fergus McFadden looked odds on to score but a last ditch tackle by Hook halted the movement. However Isa Nacewa opted to drop a goal rather than go for a try but his wobbly effort put Leinster 11-12 ahead.
The Ospreys continued to struggle in the scrums with Paul James pinged at the set piece and Sexton rifled over a long range effort to edge Leinster further ahead in a tight contest. With 10 minutes left the home side found themselves behind at 11-15.
Sexton then bisected the uprights with his fifth penalty after Lee Byrne was penalised for not releasing the ball after a great chip and catch. The successful kick saw home fans leave in streams with six minutes still to play.
The Ospreys finished the match on the attack searching for a try to give their home fans something to cheer about but ex-All Blacks star Marty Holah inexplicably kicked the ball down the throats of Leinster who gleefully kicked the ball dead to ensure the pressure will mount on an under performing side.
