Dan Biggar kicked six penalties to steer the Ospreys back from the brink of defeat as they overturned a 13 point deficit to beat Ulster 23-22 at the Liberty Stadium.
The axed Welsh outside half guided the Magners League champions to a much needed victory that keeps them in touch with the top four teams on a weekend when two of them slipped up away from home.
The Scarlets were pipped in Connacht and runaway leaders Munster were overturned in Treviso, so the Ospreys needed to make the most of the weekend by closing the gap on the front runners for the four Play-Offs places on the road to the second Magners League Grand Final on Saturday, 28 May.
The four points looked a long way off after Ian Humphreys had given Ulster a 13-0 lead with two penalties and then a penalty try which he also converted. In much the same way as they had blown away Cardiff Blues on their last visit to Wales, when they ran out 37-15 winners, Ulster scored at almost a point a minute in the opening quarter to create what looked like being a winning platform.
But after that bright opening the Ospreys scrum began to turn the screw and the penalties flowed as the Ospreys finally got their act together.
That allowed Biggar to prove he can still hit the mark with his goalkicking as he landed six out of eight attempts to punish the visitors. One of his penalties was a monster from 55 metres on the stroke of half-time that gave the home side the lead for the first time at 14-13.
As well as Biggar's three penalties the Ospreys also conjured up a corner try for ex-All Black flanker Marty Holah which owed much to the skill and vision of Ashley Beck, who threw a long, cut out pass to create the opening.
Two silly home indiscretions at the start of the second half allowed Pienaar, who took over at outside half from Humphreys when he left the field with a shoulder problem after 31 minutes, to show off his considerable goalkicking skills and Ulster suddenly found themselves five points clear.
But Biggar replied with three more penalties, two for scrum offences, and not even a third strike from Pienaar six minutes from time could claw back the deficit.
Scorers:Ospreys: Try: M Holah; Pens: D Biggar 6. Ulster: Penalty Try; Con: I Humphreys; Pens: R Pienaar 3, I Humphreys 2
The Welsh Rugby Union has announced a major new sponsorship deal with Gullivers Sports Travel which will make the UK's leading, and longest established, multi-sport tour operator, an Official Supplier for the rest of the decade.
Having taken part in seven World Cups as a player and coach, Liza Burgess hopes to go out in style this afternoon when Wales take on Australia in the Play-off for seventh and eighth place in the Women's Rugby World Cup in Paris.
WRU Head of Rugby Josh Lewsey met with volunteers across the game earlier this week, championing their role in the sport. He was joined by Wales captain Sam Warburton for part of the day as volunteers took part in a 'Try Out' event for the 2015 Rugby World Cup
Wales Women may not have got the results they wanted recently on the field, but off it they have made massive strides in strength and conditioning - and that is in no small part due to S&C coach Sam Dodge.
Two weeks into the new pitch project at Millennium Stadium, Groundman Craig Campbell takes staff on a unique behind-the-scene tour of the works so far and National Squad Assistant Strength and Conditioning Coach John Ashby and Tour Guide Peter Owen describe what the revamp means for them.
Try-scorer Jenny Davies and fellow prop Megan York reveal to WRU TV's Graeme Gillespie their thoughts after Wales broke their drought in the Women's Rugby World Cup with a 35-3 win over South Africa in Paris.
Wales Women are expecting a tough battle against South Africa on Saturday as both teams seek their first pool win of the Rugby Women's World Cup. WRU TV's Graeme Gillespie talks to head coach Rhys Edwards and lock Jenny Hawkins.
Wales' Sam Warburton took a group of employees from Admiral on a behind the scenes tour of the Millennium Stadium and WRU TV tagged along to bring you a snippet of what it's like for the players on match day