Ospreys (5) 8
Try: Parker Drop-goal: Biggar
Leinster (0) 13
Try: D'Arcy Con: Contepomi Pens: Contepomi (2)
Highlights - Ospreys 8-13 Leinster
Leinster condemned the Ospreys to their second home defeat of the season as the reigning champions won 13-8 to move to the top of the Magners League.
The strong Irish region came from behind to beat a patched-up Ospreys, who did claim a losing bonus point.
Sonny Parker gave the hosts a first-half lead before Leinster's Gordon D'Arcy charged over when the Ospreys were without sin-binned Filo Tiatia.
Felipe Contepomi added the conversion to his two penalties to seal victory.
But Dan Biggar, who had missed two penalties and a conversion, rescued a bonus point in the final minute with a drop-kick from 20 metres out.
Parker's 39th-minute score broke the deadlock in an uninspiring first-half.
The former Wales centre broke through three would-be tacklers, including Stan Wright and Cameron Jowitt, to cross before the try was awarded on the advice of the television match official.
And the Ospreys, without 16 internationals away on Six Nations duty, survived a scare thanks to the very same official.
Ospreys prop Cai Griffiths, it was ruled, had got underneath Leinster number eight Ricky Elsom's attempt to cross the line following a Shane Jennings' kick and chase ahead which was well defended by Ed Shervington and David Bishop.
Biggar was off target with the only penalty goal attempt of the first-half from 45 metres out but the Irish team took just two minutes of the second period to cut the Ospreys lead to two points with a Contepomi penalty.
And the experienced fly-half gave Leinster the lead after 54 minutes with a second penalty in the incident when where Tiatia was yellow carded for killing the ball on his own try-line.
With the extra man, Leinster's greater experience began to tell as they scored a try through D'Arcy after a break by Contepomi into the 22 as the Ospreys' defence was called into question.
Contepomi followed Tiatia into the sin-bin for a professional foul as the Ospreys tried to make a dent in the eight-point deficit.
The Welsh region squandered the chance of grabbing a losing bonus point in injury time as Jonny Vaughton's pass to an unmarked Tiatia on the touchline was wayward.
Biggar's late drop-goal was the Ospreys' only consolation for a team who had earlier been dealt a blow when highly-rated rookie wing Kristian Phillips had to go off with a dislocated shoulder, an injury that rules him out of next week's Wales Under-20 v Italy Under-20 game.
Leinster also suffered an injury setback when wing Isa Nacewa was stretchered off in the first-half as the Ospreys' title hopes were dealt a huge blow in front of their own fans.
Ospreys: Owen, K. Phillips, Parker, A. Bishop, Vaughton, Biggar, Nutbrown, James, Shervington, Griffiths, Levi, Lloyd, Smith, Holah, Tiatia.
Replacements: Spratt for Owen (60), D. Bishop for K. Phillips (14), Baldwin for Shervington (80), Mitchell for Griffiths (80), Tandy for Lloyd (66). Not Used: Pitman, Wells.
Leinster: Dempsey, Horgan, McFadden, D'Arcy, Nacewa, Contepomi, O'Donohoe, Healy, Jackman, Wright, Hogan, O'Kelly, Jowitt, Jennings, Elsom.
Replacements: Sexton for McFadden (48), S. Keogh for Nacewa (25), Whitaker for O'Donohoe (48), Blaney for Jackman (50), Toner for Hogan (60), O'Brien for Jowitt (42). Not Used: Knoop.
Ref: Peter Fitzgibbon (Ireland).