The Ospreys stole a march on the Blues in the battle for the last Welsh Heineken Cup spot with a comprehensive Celtic League win at St Helen's.
Ospreys (23) 34
Tries: Connor, Newman, Henson
Cons: Henson (2)
Pens: Henson (5)
Blues (6) 13
Pens: Robinson (2)
First-half tries from Shaun Connor and Andy Newman gave the Ospreys control.
Fly-half Gavin Henson stole the show, landing seven superb kicks at goal, tackling bravely and rounding the game off with a last-minute try.
Jon Vaughton got a try for the Blues as part of a second-half rally, but the Ospreys defence held out.
The Ospreys started the hungrier of the two sides, Wales prop Adam Jones - back after an ankle injury that had kept him out
for a month - helping their pack establish supremacy.
Connor opened the scoring in the fourth minute, running a midfield loop off James Storey from good scrum ball and cruising
untouched through the Blues defence.
Nicky Robinson pulled back a penalty, but the lacklustre Blues were caught napping from a line-out, Barry Williams peeling
off the front and feeding Newman who crashed over for a rare score.
Robinson added another penalty but saw Henson outmatch him with two fine efforts.
The Blues had a chance to get right back in the game when Ospreys flanker James Bater was sin-binned in the 32nd minute after
lying on the wrong side of the ruck.
Robinson missed two simple penalty shots with the Ospreys down to 14 men, though, and just before the break a Henson strike
extended his team's lead to 23-6.
Blues' hopes were raised at the start of the second half when Robinson broke deep in his own half and fed Vaughton, the
former Swansea wing sent free on a 35m sprint to the line.
The Blues failed to match the Ospreys' intensity
Henson landed his fourth penalty, but the Blues pressure mounted throughout the second half, even the substitute appearance
of Wales prop Paul James failing to help the Ospreys regain control.
But for all the territory and possession enjoyed by the visitors the Ospreys defence held firm, the mood typified by Henson
who denied Nick Walne in the corner with a last-ditch tackle.
After 67 minutes the Blues had a Nathan Thomas try disallowed following a forward pass from Robinson, and the visitors' last
chance had gone.
Matt Cockbain ended his time with the Blues before heading to Japan with 10 minutes in the sin bin after failing to retreat
from a quickly taken Ospreys penalty.
Henson landed the resultant shot at goal, and rounded off the game with a last-minute try in a flying Ospreys finish.
"The first 20 minutes of each half were crucial, they set the tone for the game and left them chasing it," said Ospreys scrum-half Andy Williams.
"Our forwards, especially Luke Tait, were superb, and when it's like that you get an armchair ride as a scrum-half.
"The win shows the character in this young side. (Coach) Lyn Jones has been superb, he knows our weaknesses and has worked on them."
Ospreys: Henson, Terblanche, Storey, Tiueti, Seveali'i, Connor, Williams, Millward, Williams (capt), Jones, Newman, Tait, Bater, Tandy, Lloyd.
Replacements: Durston, Wells, James, Wells, Bateman, Pugh, Bonner-Evans.
Blues: Van Vuuren, Walne, J Robinson, Muller, Vaughton,
N Robinson, A Moore, Fourie, Lewis, Crompton, Quinnell,
A Moore, Cockbain, Baugh, N Thomas.
Replacements: Evans, R Thomas, Brownrigg, Sowden-Taylor,
Powell, Macleod, Allen.
Referee: Olan Trevor (Ireland).