Shane Williams signed off in fairytale fashion as his try double helped the Ospreys edge out Leinster 31-30 in an epic six-try RaboDirect PRO12 shootout.
In his last ever game for the Welsh region, the diminutive winger ducked out of Rob Kearney's challenge to wriggle over in the right corner for a 78th-minute try. Williams' score made it a one-point game and Dan Biggar showed nerves of steel to land the conversion, etching the Ospreys into the record books as the first team to win four league titles.
Leinster had lead 17-9 at half-time thanks to tries from Sean Cronin and Isa Nacewa, and another from the Fijian international gave them a 30-21 advantage after Ashley Beck and Williams had crossed for the Ospreys. But Williams stunned the RDS crowd late on before Biggar converted to deny Leinster a famous European and domestic double.
Steve Tandy's side had beaten the Heineken Cup champions twice during the regular season and they nipped ahead thanks to a ninth-minute penalty from Biggar only for Jonathan Sexton to cancel it out with three points of his own.
Biggar restored the Osprey's lead but Leinster hit back when Brian O'Driscoll brilliantly drew in two defenders to set hooker Cronin free for a rampaging run to the line. Sexton converted with aplomb, a quality kick which was matched by the in-form Biggar as he topped off a powerful scrum with his third successful penalty.
However, Sexton's pinpoint restart kick was fielded superbly by a leaping Nacewa and the winger burst through for an opportunist try. That defensive lapse was further punished by Sexton adding the extras from wide out, although the Ospreys quickly got back on the front foot in the second half.
The Welshmen had the try they craved just 84 seconds into the second half. Joe Bearman's clever offload released centre Beck for a well-taken seven-pointer but Leinster replied almost immediately, Sexton rifling over his second penalty.
Sexton kicked Leinster 23-16 ahead but in yet another twist, the Ospreys worked numbers on the left to release Williams for a rare scoring chance and he showed his renowned finishing skills by crashing over past Eoin Reddan.
Biggar missed the conversion, leaving Leinster with a two-point buffer, and the league's table-toppers seemed to be turning the screw when Nacewa swooped for his second of this closely-fought final. Sexton's conversion completed his 15-point haul and pushed the margin out to nine points with just 16 minutes remaining.
But, after Biggar sent over another penalty to give his team-mates renewed hope, ace poacher Williams had enough of a sniff to go for the kill and pen the fairytale finish. He passed the baton to Biggar, possibly one of Welsh rugby's future stars, to loft over the match-winning kick.