Sexton hits peak form to lift Blues to summit
Ospreys 9 Leinster 22
Jonathan Sexton came out on top in his personal duel with Dan Biggar as Leinster's seventh successive Guinness Pro12 victory moved Leo Cullen's men to the top of the table.
Sexton, who had struggled to find his best form since returning from Racing Metro, was imperious in a man-of-the-match display.
The Ireland out-half kicked seven points and played a key hand in tries for Dave Kearney and Noel Reid, with the winger adding his second late on to seal the win.
Biggar, meanwhile, kicked all his side's points, but missed two kickable penalties during an important period to allow his opposite number to take the bragging rights ahead of their meeting in the opening round of the Six Nations.
This was an ultimately emphatic victory for Leinster, and it was the first against the Ospreys on their home patch in the league since 2009.
They even overcame injuries to Jamie Heaslip and Luke Fitzgerald, which may yet give Joe Schmidt cause for concern, on a pleasing night for Cullen and his staff.
They had looked the stronger side on paper, with the Ospreys having to shuffle their pack and resting Alun Wyn Jones and Justin Tipuric with European commitments in mind.
Without Champions Cup concerns to burden him, Cullen was able to name a strong side and the extra experience and nous proved crucial in challenging conditions.
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Leinster made a promising start, enjoying an extended spell in Ospreys territory after a poor early clearance from Biggar.
The visitors worked their way through phase after phase, forcing the Welshmen to make an extraordinary 22 tackles inside the opening six minutes of play, but could not break down a dogged defence despite positive surges by Sexton and Ben Te'o.
The metaphorical pain of an early missed chance was soon added to by the very real pain felt by skipper Heaslip. The Ireland No 8 clashed heads with Te'o as Ospreys wing Jeff Hassler bludgeoned his way between the two would-be tacklers.
Play continued with Heaslip flat out on the deck and it quickly became clear he would not be continuing as he struggled to find his feet as he tried to get up, with Dominic Ryan quickly summoned from the bench.
The flanker was soon into defensive action as Ospreys opted to put a kickable penalty into the corner and battered away at the line, only for a tough tackle from Richardt Strauss to dislodge the ball.
Biggar made up for the near miss with a clinically taken drop-goal in the 15th minute, but it was soon Sexton who was the centre of attention.
He gave the Ospreys a warning as one perfect cross-kick found Isa Nacewa and left the home defence scrambling. However, the lesson was not learnt and when Sexton went to the opposite wing a few minutes later, Kearney fielded the kick and carried Hassler over the line with him.
Sexton added the extras and was at the heart of the action, winning a penalty after a late hit from Sam Underhill as he cleared his lines, before making an important strip on centre Owen Watkin.
Biggar settled the Ospreys after a difficult period with his second penalty but Sexton soon replied in kind as his clever kick isolated Brendon Leonard and allowed Sean O'Brien to force the penalty.
The visitors had enjoyed the edge in the tight exchanges but were penalised for wheeling the scrum just before half-time. However, Biggar let them off the hook as he dragged his attempt wide, and Leinster led 10-6 at the break.
Ill-discipline allowed the Ospreys good field position immediately after the resumption, with Strauss giving away a penalty and Sexton making a rare error deep in his own territory under pressure from Sam Underhill, but solid Leinster defence managed to hold the hosts at bay on the line.
Biggar was off-target when the Leinster scrum were again penalised for walking round, but made amends when O'Brien infringed on the floor.
The Ireland flanker was then left further frustrated when he could not cling on to loose ball, with the tryline beckoning him.
However, Leinster did not have to wait long to celebrate their second try. Sexton spotted an overlap and shifted the ball wide through Reid to Te'o. The Worcester-bound centre committed two defenders and offloaded back to the replacement, who raced over in the corner.
Sexton struck the post with the conversion to keep the Ospreys within range, but Kearney slid home from a set scrum move to put the result beyond doubt.
Ospreys - D Evans (S Davies 18-30); J Hassler (E Walker 32), J Spratt, O Watkin (S Davies 68), H Dirksen; D Biggar, B Leonard (T Habberfield 70); P James (N Smith 59), S Baldwin, A Jarvis (M Fia 63), L Ashley, R Thornton (AW Jones 56), J King, S Underhill (J Tipuric 63), D Baker.
Leinster - R Kearney; I Nacewa, B Te'o, L Fitzgerald (N Reid 63), D Kearney; J Sexton (I Madigan 76), L McGrath (E Reddan 62); J McGrath (P Dooley 69), R Strauss (S Cronin 56), T Furlong (M Moore 56), D Toner, M McCarthy (T Denton 71), R Ruddock, S O'Brien, J Heaslip (D Ryan 7).
Ref - David Wilkinson (IRFU)