The Ospreys secured a convincing 33-12 RaboDirect Pro12 derby win over the Blues at the Liberty Stadium in Swansea.
The Ospreys were searching for their first win in three following consecutive defeats to Exeter and Edinburgh, while the Blues were seeking back-to-back wins following their recent triumph over Zebre.
Matthew Morgan got the scoring underway for the Ospreys with a tenth-minute penalty, and barely two minutes later he added the conversion after James King got on the end of a well-worked move from the line-out to cross for a try in the corner.
The Ospreys continued to control proceedings for the remainder of the first half and they took their ten-point advantage with them into half-time, as two Morgan penalties cancelled out two Cardiff three-pointers booted over by Ceri Sweeney.
Two minutes into the second half, Richard Fussell touched down after following up a speculative Ross Jones grubber kick to put further distance between the two sides, with Morgan again adding the conversion.
But shortly after, Sam Lewis was sent to the sin-bin for the hosts after being caught offside, allowing Rhys Patchell the opportunity to narrow the deficit with the boot.
He added his second penalty of the evening five minutes later, before Morgan restored the 14-point advantage with a three-pointer of his own on the hour.
The Blues searched for a route back into the contest in the final quarter, but came up short, and in the final minute Morgan Allen rounded off the scoring for the Ospreys with a well-taken try from the line-out, again converted by Morgan, who finished the evening with 18 points to his name.
Tries: King, Fussell, Allen
Cons: Morgan 3
Pens: Morgan 4
For Cardiff Blues:
Pens: Sweeney 2, Patchell 2
Ospreys: 15 Richard Fussell, 14 Ross Jones, 13 Tom Isaacs, 12 Andrew Bishop, 11 Eli Walker, 10 Matthew Morgan, 9 Kahn Fotuali'i (c), 8 Joe Bearman, 7 Sam Lewis, 6 George Stowers, 5 James King, 4 Ian Gough, 3 Cai Griffiths, 2 Scott Baldwin, 1 Duncan Jones.
Replacements: 16 Matthew Dwyer, 17 Marc Thomas, 18 Dmitri Arhip, 19 Lloyd Peers, 20 Morgan Allen, 21 Rhys Webb, 22 Sam Davies, 23 Jonathan Spratt.
Cardiff Blues: 15 Rhys Patchell, 14 Tom Williams, 13 Gavin Evans, 12 Dafydd Hewitt, 11 Owen Williams, 10 Ceri Sweeney, 9 Lloyd Williams, 8 Robin Copeland, 7 Josh Navidi (c), 6 Rory Watts-Jones, 5 James Down, 4 Michael Paterson, 3 Taufa'ao Filise, 2 Marc Breeze, 1 Sam Hobbs.
Replacements: 16 Andi Kyriacou, 17 Nathan Trevett, 18 Benoit Bourrust, 19 Macauley Cook, 20 Andries Pretorius, 21 Lewis Jones, 22 Gareth Davies, 23 Jason Tovey.
Referee: Leighton Hodges