The Ospreys maintained their slim Magners League title hopes with a tense 19-17 victory over current leaders Leinster at the Liberty Stadium on Friday.
Once again James Hook was the hero for the Ospreys, coming on as a second-half replacement and kicking three penalty goals to give his side a valuable win.
Hook's 76th-minute penalty preserved the Welsh side's unbeaten home record this season and ensured the title will go right down to the wire.
Tries from Shane Horgan and Felipe Contepomi looked to have done enough to give the Irish province a smash-and-grab win against their dominant Welsh hosts.
But Wales international Hook had the last say when he kept his nerve to help the Ospreys turn around a 17-10 deficit to snatch victory.
Shaun Connor and Contepomi swapped early penalties before the Ospreys made the most of their dominance when scrum-half Justin Marshall raced through under the sticks for a converted score.
But after the Ospreys squandered a host of opportunities Leinster hit them against the run of play when Horgan intercepted Marshall's long pass to race clear and challenge under the posts to make it 10-10 at the interval.
Argentine star Contepomi gave the visitors the lead for the first time moments into the second half when he jinked his way over after Rob Kearney and Chris Whitaker had combined, with Contepomi adding the extras.
The Ospreys sent on Hook and he made an immediate impression with two penalties.
And when Leinster's Jamie Heaslip was sin-binned in the final quarter, Hook and the Ospreys made the most of the numerical advantage to clinch the win.
For The Ospreys:
Pens: Connor, Hook 3
Tries: Horgan, Contepomi
Con Contepomi 2
Ospreys: 15 Stefan Terblanche, 14 Nikki Walker, 13 Sonny Parker, 12 Andrew Bishop, 11 Shane Williams, 10 Shaun Connor, 9 Justin Marshall, 8 Filo Tiatia, 7 Richard Pugh, 6 Ryan Jones, 5 Alun Wyn Jones, 4 Jonathan Thomas, 3 Adam Jones, 2 Huw Bennett, 1 Paul James (capt).
Replacements: 16 Richard Hibbard, 17 Duncan Jones, 18 Mike Powell, 19 Lee Beach, 20 Martin Roberts, 21 James Hook, 22 Lee Byrne.
Leinster: 15 Girvan Dempsey, 14 Rob Kearney, 13 Shane Horgan, 12 Gordon D'Arcy, 11 Luke Fitzgerald, 10 Felipe Contepomi (c), 9 Chris Whitaker, 8 Jamie Heaslip, 7 Keith Gleeson, 6 Stephen Keogh, 5 Malcolm O'Kelly, 4 Trevor Hogan, 3 Will Green, 2 Brian Blaney, 1 Reggie Corrigan.
Replacements: 16 Stan Wright, 17 Bernard Jackman, 18 Owen Finegan, 19 Cameron Jowitt, 20 Guy Easterby, 21 Christian Warner, 22 Kieran Lewis.
Referee: Peter Allan (SRU)
Touch judges: Nigel Owens (WRU), Jonathan Mason (WRU)