Cardiff Blues ensured that the Ospreys' difficult week continued by winning 28-9 in Swansea at the Liberty Stadium.
Ospreys: (6) 9:
Pens: Connor 2, Cashmore.
Blues: (14) 28:
Tries: D Jones, Czekaj, Morgan.
Cons: N Robinson 2.
Pens: Robinson 3.
Gavin Henson and Ian Evans face a disciplinary hearing on Friday after being cited for incidents in last weekend's European loss to Leicester.
The pair both played for the Ospreys on Thursday night but neither were able to halt a dominant Blues display.
Deiniol Jones opened the scoring for the visitors, with wings Chris Czekaj and Craig Morgan adding further tries.
It was the Blues' first victory on the road against a fellow Welsh side since regions were introduced in 2003.
The only downside for Blues coach Dai Young is he now has the headache of choosing between three wingers in confident mood, with former All Black star Jonah Lomu rested for this encounter.
It took the Blues just seven minutes to break through their hosts.
Mike Phillips made the initial break after taking a quick tap penalty, bursting through the first line of defence and finding Morgan in support.
The wing was brought down but the ball was recycled and eventually found its way out left, where lock Deiniol Jones cantered over for a try converted by Nick Robinson.
Connor fluffed a simple penalty chance from in front of the posts, but a fine break from Sonny Parker - brushing through Jamie Robinson's powder-puff tackle - earned a second chance.
The fly-half made no mistake this time, as Connor opened the Ospreys' scoring account.
But the Blues stretched their lead further when a forward drive sucked in the cover and then Jamie Robinson made amends for his earlier mistake by creating the visitors' second try.
The outside centre picked a superb line to bust what was left of the Ospreys defence, before floating the killer pass long and wide to right wing Czekaj.
Nick Robinson was again on target with the conversion, although Connor pulled the score back to 14-6 with his second penalty.
Phillips was sin-binned for a high tackle on Ospreys number eight Jon Thomas, but the Blues still managed to dominate the remainder of the half.
Another Jamie Robinson break just before half-time should have given Czekaj his second try of the night, only for Shane Williams - restored to the Ospreys starting line-up - to prevent his opponent grounding the ball.
Williams is getting married on Friday and hopefully he will be given less of a runaround during the nuptials than in this match.
After the restart Nick Robinson struck two swift penalties for the Blues, although Ospreys full-back Adrian Cashmore replied with one of his own.
Then Phillips' quick thinking, taking another tap, allowed Nick Robinson to send Morgan over untouched in the left corner for an unconverted try.
The Ospreys laboured to gain any headway as the Blues pack, led superbly by streetwise Kiwi Xavier Rush, grappled and grunted their opponents to a standstill.
A final Nick Robinson penalty pushed the Blues' lead to 28-9 to record a hugely encouraging victory for the side from Cardiff.
Cardiff Blues coach Dai Young:
"There weren't many things we did poorly and we played as a team.
"We could have been a bit more clinical, but I'm really struggling to fight back a big smile because it was a great performance and I'm thrilled.
"Not many teams come here and get the result and I'm over the moon - we've set the standard now."
Ospreys: Adrian Cashmore; Richard Mustoe, Sonny Parker, Gavin Henson, Shane Williams; Shaun Connor, Jason Spice; Duncan Jones, Barry Williams (capt), Adam Jones, Andrew Newman, Ian Evans, James Bater, Steve Tandy, Jonathan Thomas.
Replacements: Stefan Terblanche for Mustoe (63), Matthew Jones for Connor (41), Huw Bennett for B Williams (63), Des Dillon for Thomas (63). Not Used: Andrew Millward, Lyndon Bateman, Andrew Bishop.
Cardiff Blues: Rhys Williams (capt); Chris Czekaj, Jamie Robinson, Marc Stcherbina, Craig Morgan; Nick Robinson, Mike Phillips; Gethin Jenkins, Rhys Thomas, Martin Jones, Deiniol Jones, Robert Sidoli, Andy Powell, Martyn Williams, Xavier Rush.
Replacements: Duane Goodfield for R. Thomas (63), Craig Quinnell for D. Jones (55), Robin Sowden-Taylor for Rush (6). Not Used: Ben Evans, Ryan Powell, Roger Warren, Tristan Davies.
Referee: Phil Fear (WRU).