A Justin Tipuric try and the boot of Dan Biggar helped Ospreys to a 22-19 victory over Cardiff Blues.
Despite the Blues grabbing a try through Kristian Dacey in the first-half, the Ospreys still went into the break leading thanks to Biggar's boot.
And after Tipuric had spotted a gap to dot the ball down the game was out of the reach of the home side, despite Leigh Halfpenny reducing the arrears from the kicking tee.
In the end the Blues just ran out of time as the Ospreys held on for the win, their tenth straight against a fellow Welsh region.
With just two minutes on the board Halfpenny had the chance to get the Cardiff Blues on the scoreboard which he duly took as he knocked over a penalty.
But just three minutes later Ospreys were level thanks to a superb long-range drop goal from Biggar.
Moments later Biggar then charged down Gareth Davies' attempted clearance but the flyhalf couldn't quite gather the loose ball in as it went dead, although on 11 minutes he did put the Ospreys in front as he knocked over a penalty.
Halfpenny had a chance to level the game once again with a three-pointer of his own but the British and Irish Lion uncharacteristically failed to convert from right in front of the posts.
And the Cardiff Blues star missed another kick at the posts from 40m out after Biggar had stretched the Ospreys lead further, showing Halfpenny how it is done from the tee.
However Halfpenny made amends as he helped create the first try of the game on 28 minutes.
The fullback started a Blues counter-attack, feeding Harry Robinson who was only denied a try by a great tackle from Hanno Dirksen, but the ball found its way to Dacey, the hooker bouncing off Adam Jones before touching down.
Halfpenny slotted the conversion and the Blues re-took the lead.
This woke the Ospreys up and they had a period of sustained pressure just feet from the Cardiff Blues try-line but the home side's defence held firm.
However two more Biggar penalties saw Ospreys go into half-time with a 15-10 lead.
Halfpenny reduced the arrears with a penalty shortly after the restart but just as it looked like the Blues would get back into the game momentum swung back into the Ospreys' favour as Tipuric went over, coming off the back off the maul before spotting a hole and squeezing over.
Biggar adding the conversion and suddenly the Ospreys had some breathing space as they had a nine-point lead.
However the Blues weren't about to lie down and through some sustained pressure they slowly began to chip away at their visitors' lead through two Halfpenny penalties - Ospreys going down to 14 men in between as replacement Marc Thomas was sin-binned.
But despite some pressure the Blues couldn't find another score and had to settle for a losing bonus point and are still searching for a first PRO12 win over Ospreys since December 2010.
For Cardiff Blues:
Pens: Halfpenny 4
Pens: Biggar 4
Cardiff Blues: 15 Leigh Halfpenny, 14 Alex Cuthbert, 13 Richard Smith, 12 Dafydd Hewitt, 11 Harry Robinson, 10 Gareth Davies, 9 Lloyd Williams, 8 Robin Copeland, 7 Rory Watts-Jones, 6 Andries Pretorius, 5 Filo Paulo, 4 Macauley Cook, 3 Benoit Bourrust, 2 Kristian Dacey, 1 Sam Hobbs (captain).
Replacements: 16 Rhys Williams, 17 Thomas Davies, 18 Scott Andrews, 19 James Down, 20 Josh Navidi, 21 Lewis Jones, 22 Gavin Evans, 23 Chris Czekaj.
Ospreys: 15 Sam Davies, 14 Hanno Dirksen, 13 Tom Isaacs, 12 Ben John, 11 Aisea Natoga, 10 Dan Biggar, 9 Tom Habberfield, 8 Joe Bearman, 7 Justin Tipuric, 6 Sam Lewis, 5 James King, 4 Alun Wyn Jones (captain), 3 Adam Jones, 2 Scott Baldwin, 1 Ryan Bevington.
Replacements: 16 Matthew Dwyer, 17 Marc Thomas, 18 Dan Suter, 19 Morgan Allen, 20 Tyler Ardron, 21 Tito Tebaldi, 22 Ashley Beck, 23 Jeff Hassler.
Referee: Jérôme Garcès (France)
Assistant referees: Rhys Thomas (Wales), Sean Brickell (Wales)
TMO: Gareth Simmonds (Wales)
Edinburgh 11-6 Leinster
Greig Laidlaw returned to the side to help Edinburgh record an 11-6 win over reigning PRO12 champions Leinster and make it five wins from seven in all competitions.
Laidlaw was one of a trio of Scottish internationals rested by head coach Alan Solomons for last week's European Cup win over Gloucester.
And he returned refreshed and raring to go, kicking two penalties and making a series of impressive breaks as Edinburgh recorded their first victory over the Irish side in six attempts.
Dougie Fife dotted down for the only try of the game in the first half as Leinster, who recorded two Ian Madigan penalties, suffered their first PRO12 defeat since round five against Munster.
With driving rain and windy conditions, it was always going to be a difficult night for flowing rugby and the early exchanges reflected that with several knock ons from both side.
Edinburgh were having the better of the early scrum exchanges, and an early penalty against Leinster on ten minutes saw Greig Tonks punt the ball long for a Edinburgh line out, but it failed to come to anything.
Leinster threatened to mount an attack on 17 minutes with a quick move that saw them move to within five metres of the line.
And while the hosts defence held firm, Leinster did get the first points of the game on the board four minutes later as Madigan kicked a simple three points from in front of the posts for a 3-0 lead.
But the hosts got themselves in front on the half hour mark when Fife slide over the near corner, although the beginning of the move came from a marauding run by Laidlaw a good five minutes earlier.
From then it was all about patient Edinburgh pressure and when Tonks asked for the ball on the left, he spun the ball to Fife for an easy score, Laidlaw pulling his conversion wide to leave the score at 5-3.
The momentum was with the hosts with the forwards making sure to leave their mark, as a driving maul was edged towards the Leinster line.
And when the visitors were penalised for coming in from the side, Laidlaw gratefully took the three point option to put his side 8-3 up heading into the break.
A second Madigan penalty shortly after the break brought Leinster back to within two points but with Leinster penalised for not released, Laidlaw was on hand to slot over his second penalty of the game to leave the score at 11-6 after 46 minutes.
Edinburgh were continuing to enjoy more of the territory and another fine break from Laidlaw brought them into the Leinster 22 before he chipped over and Leinster ran the ball out just five metres from their line.
From the resulting set piece, Cornell du Preez looked to navigate his way through to line but after being held up, he was pinged for not releasing and Leinster cleared.
Laidlaw had an opportunity to extend his side's lead to eight points on 74 minutes but he was unable to convert on the angle with the scores staying at 11-6.
Leinster were not about to throw in the towel just yet as they launched one last attack, but despite pummelling the line with two minutes to go, a knock on handed Edinburgh the scrum.
Leinster put pressure on but the hosts watched the clock down for Laidlaw kicked into touch to confirm victory.
Pens: Laidlaw 2
Pens: Madigan 2
Edinburgh: 15 Jack Cuthbert, 14 Dougie Fife, 13 Nick De Luca, 12 Ben Atiga, 11 Tom Brown, 10 Greig Tonks, 9 Greig Laidlaw (captain), 8 Dave Denton, 7 Roddy Grant, 6 Cornell du Preez, 5 Ollie Atkins, 4 Grant Gilchrist, 3 WP Nel, 2 Ross Ford, 1 Al Dickinson.
Replacements: 16 Aleki Lutui, 17 Wicus Blaauw, 18 Geoff Cross, 19 Sean Cox, 20 Mike Coman, 21 Grayson Hart, 22 Tony Fenner, 23 Sam Beard.
Leinster: 15 Zane Kirchner, 14 Darragh Fanning, 13 Brian O'Driscoll, 12 Noel Reid, 11 Luke Fitzgerald, 10 Ian Madigan, 9 Isaac Boss, 8 Jordi Murphy, 7 Shane Jennings, 6 Kevin McLaughlin, 5 Tom Denton, 4 Leo Cullen (captain), 3 Martin Moore, 2 Aaron Dundon, 1 Michael Bent.
Replacments: 16 James Tracy, 17 Jack O'Connell, 18 Tadhg Furlong, 19 Quinn Roux, 20 Dominic Ryan, 21 John Cooney, 22 Jimmy Gopperth, 23 Brendan Macken.
Referee: Peter Fitzgibbon (Ireland)
Assistant Referees: Andrew McMenemy, TBC (both SRU)
TMO: Iain Ramage (SRU)
Ulster 13-6 Zebre
Jared Payne's first-half try helped Ulster overcome a stubborn Zebre outfit 13-6 for their fourth PRO12 home win in a row on Friday night.
Early penalties from Luciano Orquera and Tommaso Iannone had put second-bottom side Zebre into an early lead before Ulster hit back through Payne's try before the break.
Ruan Piennar would also contribute eight points with his boot as the hosts, who welcomed back leading Ulster appearance holder Paddy Wallace after nine months out with an ACL injury, continued their winning record against Italian sides.
Zebre's only PRO12 victory this season came against Cardiff Blues back in Round Three, and despite being winless in ten in all competitions, they had the stronger start, with Orquera notching an early penalty.
With wind proving to make things difficult for the kickers, the Zebre flyhalf was unable to add to his tally five minutes later as he pulled his shot from the halfway line wide.
But despite having never won away from home in the PRO12, the visitors were giving a good account of themselves.
And when Callum Black was penalised at the scrum, Iannone, assuming kicking duties with Orquera off the pitch injured, slotted over a second penalty to give Zebre a 6-0 lead on the quarter-hour mark.
Ulster were starting to get themselves back in the game but after peppering the Zebre line, the TMO spotted a stamp by Johann Muller and the move broke down.
But they got themselves ahead ten minutes before the break, as the ball was spread wide from a line out to Payne and despite having Wallace in support, the fullback opted to go it alone, jinking in under the posts, Pienaar with the extras.
Zebre hit back straight away as wing Leonardo Sarto evaded four Ulster tackles to break towards the line, but while awarded a penalty shortly afterwards, Ulster's defence held firm from the resulting line out.
It proved to be the last meaningful action of the half, as Ulster headed into the break one point ahead.
That difference would be extended to four points nine minutes into the second half as Pienaar knocked over a penalty from in front of the posts.
Ulster, with the wind in their favour now, were cranking up the pressure, enjoying plenty of territory although Zebre's spirited defence meant they failed to really threaten.
With Zebre only four points behind, Ulster knew they needed more of a cushion heading into the final ten minutes against their spirited opposition.
So it came as no surprise that Pienaar opted to kick for goal when Zebre's ill discipline at the breakdown handed Ulster a penalty on 72 minutes, the South Africa duly obliging for 13-6.
The Italians now needed a converted try to even take a draw but Ulster kept the pressure on until the end, although Zebre did at least pick up a losing bonus point.
Pens: Pienaar 2
Pens: Orquera, Iannone
Ulster: 15 Ricky Andrew, 14 Craig Gilroy, 13 Jared Payne, 12 Paddy Wallace, 11 Michael Allen, 10 James McKinney, 9 Ruan Pienaar, 8 Robbie Diack, 7 Sean Doyle, 6 Mike McComish, 5 Lewis Stevenson, 4 Johann Muller (captain), 3 Ricky Lutton, 2 Niall Annett, 1 Callum Black.
Replacements: 16 Rob Herring, 17 Tom Court, 18 Adam Macklin, 19 Neil McComb, 20 Conor Joyce, 21 Michael Heaney, 22 Peter Nelson, 23 David McIlwaine.
Zebre: 15 Dion Berryman, 14 Leonardo Sarto, 13 Tommaso Iannone, 12 Roberto Quartaroli, 11 Giovanbattista Venditti, 10 Luciano Orquera, 9 Gugliemo Palazzani, 8 Nicola Cattina, 7 Filippo Ferrarini, 6 Filippo Cristiano, 5 Marco Bortolami (captain), 4 Quintin Geldenhuys, 3 Andrea de Marchi, 2 Andrea Manici, 1 Dario Chistolini.
Replacements: 16 Tommaso D'Apice, 17 Matias Aaguero, 18 Luca Redofini, 19 Michael van Vuren, 20 Emiliano Caffini, 21 Alberto Chillon, 22 Kameli Ratuvou, 23 Brendon Leonard.
Referee: Neil Hennessy (Wales)
Assistant referees: Sean Gallagher (Ireland), Dermot Blake (Ireland)
TMO: Simon McDowell (Ireland)