They left it late but a Dan Biggar drop goal with three minutes to play secured Judgment Day victory over Cardiff Blues at Principality Stadium.
Biggar took the man of the match honours, scoring 21 points including a second half try, but his team were made to battle all the way on the final day of the regular Guinness PRO14 season.
They had taken an early lead, Alun Wyn Jones’ try putting the Ospreys in the driving seat but, despite dominating the opening quarter they trailed by seven at the break after two Blues tries in just five minutes had turned the game on its head.
The Ospreys started brightly and led inside three minutes, a 50m run from Hanno Dirksen returning Gareth Anscombe’s kick-off, early pressure rewarded with a simple three points from Biggar right in front of the posts.
As the two teams wrestled for control it was the Blues who had the next shot at goal on 13 minutes, Ospreys hands in the ruck, and Gareth Anscombe made no mistake from more than 40m out.
That drew an instant response from the Ospreys and within minutes they were celebrating the game’s first try. Jeff Hassler was the catalyst, running powerfully through the middle then Sam Cross carried well but was stopped 15m out. Then, with a penalty advantage for high tackle being played, it was the skipper who was alert at the edge of a ruck 5m out and there was no stopping him, Biggar converting.
The Blues responded with a try of their own in the 24th minute, the Ospreys going to sleep after Dan Evans had cleared to touch, Blaine Scully’s quickly taken throw releasing Anscombe who had an almost unimpeded route to the line before adding the extras to his own try, leveling it at 10-each.
Before the half hour was up the hosts had taken the lead, a scrum on the left providing the platform to attack, Steven Shingler putting through a perfectly weighted grubber that his centre partner Garyn Smith collected in his stride to score. Anscombe was again on target with the conversion.
At the other end, Biggar had another simple three pointer following a Blues offside, which meant the Ospreys trailed by four with eight minutes remaining in the first half.
Dmitri Arhip was then penalised at a scrum on the Ospreys 10m line, Anscombe splitting the posts once again.
Ashley Beck, a first half replacement for Kieron Fonotia, was then offside in front of the kicker, giving Anscombe the chance to stretch the lead to 13 as the clock ticked past 40 but his kick struck the crossbar and a knock on as the teams fought for the loose ball brought the half to a close.
HALF-TIME: CARDIFF BLUES 20-13 OSPREYS
A scrum penalty close to halfway gave Biggar the first sight of goal after the restart but, although he comfortably had the length, his kick drifted off to the left.
The Ospreys were dominating the second half, the Blues unable to exit their half, and a great steal by Cross close to the opponents line gave them an opportunity, Dan Evans stopped just short, before the TMO ruled that Scott Otten had failed to get the ball down as he powered over the line from close range.
The pressure had to tell eventually and it did in the 55th minute when, after almost 20 phases, Biggar spotted the gap in midfield to cruise through and score under the posts, his conversion leveling things.
The Blues retook the lead with 13 minutes remaining on the clock, Anscombe with the three points following a TMO intervention to bring play back for an Ospreys offence at the lineout.
As the clock ticked towards 80, a Blues hand in the ruck gave Biggar s straightforward three points and the scoreboard was tied again, this time at 23-23, with seven minutes to play.
The Ospreys pressed and got their just reward in the 77th minute, Biggar using all his experience to drop back in the pocket and slot over a drop goal that took his team back in front, a position they didn’t relinquish.
Next up for Allen Clarke’s team is the crucial Champions Cup play-off in three weeks time, full details of the fixture to be confirmed.