Ospreys (9) 19
- Tries: Walker
- Cons: Morgan
- Pens: Morgan (3)
- Drop-goal: Morgan
Leinster (10) 10
- Tries: Auva'a
- Cons: Madigan
- Pens: Madigan
Eli Walker's spectacular try gave Ospreys a hard-fought Pro12 win over European champions Leinster.
One point separated the sides at the break after three Matthew Morgan penalties followed a converted Leo Auva'a try and an Ian Madigan penalty.
Richard Fussell sliced through the Leinster defence from deep in his own half, timing his pass perfectly for lively wing Walker to score.
Morgan converted and added a drop-goal to deny Leinster a losing bonus point.
Ospreys were often on the back foot against a powerful Leinster pack, but showed tenacity in defence and a touch of flair to capitalise on a rare break.
It gave the Welsh side their sixth win from the last seven meetings with the Irish province and took them above the visitors to fifth place in the table.
Ospreys fly-half Matthew Morgan lands a late penalty to deny Leinster a losing bonus point
They rode their luck at times, and were fortunate to escape as early as the seventh minute when a try slipped through Fionn Carr's fingers when the Leinster winger failed to hold onto the ball while sliding towards the left corner.
But the visitors pounced from the resulting line-out after charging down the attempted clearance kick from Ospreys scrum-half Rhys Webb.
The ball spun towards the posts, evading the grasp of home centre Andrew Bishop, and Leinster number eight Auva'a gathered up with glee to score.
Video referee Nigel Whitehouse gave the try despite the suspicion of a knock-on, and Madigan converted.
Two Morgan penalties cut the deficit as Ospreys began to make inroads, but they needed Walker's intervention to deny Leinster a second try when Andrew Conway chased his own chip kick.
Another let-off soon followed when Madigan pulled a simple kick at goal wide, but Morgan's aim was true as he added a third penalty with the final kick of an even first half.
Webb was the next to save the home side early after the break, clinging on by his fingertips to Madigan's shirt with the try-line in the fly-half's sights.
Leinster were on top at this stage, benefiting from their numerical advantage following a yellow card to home prop Duncan Jones.
But a moment of magic from Fussell ripped open the Leinster defence for Walker's decisive try.
Full-back Fussell received a quickly taken line-out in his own 22 and sliced through the lethargic chasing defenders, finding a clear path into the opposition half.
Walker, the most dangerous player on show with ball in hand, was perfectly placed to receive Fussell's pass as he drew the final Leinster cover.
Morgan converted, putting Ospreys 16-10 ahead, and Jones's return from the sin bin was another boost as the game entered the final 20 minutes.
Leinster continued to enjoy forward dominance, but enterprising back play took Ospreys within drop-goal territory and Morgan made no mistake to take his side two scores clear with five minutes remaining.
Fussell; H. Dirksen, Isaacs, Bishop, Walker; Morgan, Webb; D. Jones, Dwyer, Rees, Peers, J. Thomas, Stowers, Lewis, Bearman.
M. Thomas for Lewis (54), Fotuali'i for Webb (57), King for Peers (59), Lewis for M. Thomas (62), Allen for Bearman (77).
Ellis, Suter, Spratt, R. Jones.
D. Jones (51).
D. Kearney; Conway, Macken, Goodman, Carr; Madigan, Boss; Van der Merwe, T. Sexton, Hagan, Browne, Toner, Ruddock, Jennings, L. Auva'a, Marshall.
Marshall for Browne (26), Murphy for Marshall (65), Moore for Hagan (68), Tracy for Auva'a (77), J. McGrath for Van der Merwe (77)
Cooney, Reid, Coghlan-Murray.
John Lacey (IRFU)
Neil Nennessy, Wayne Davies (both WRU)
Dennis Jones (WRU)
Nigel Whitehouse (WRU)