It was tight at the finish but Cardiff deservedly held on to bring the curtain down on 2010 with a much-needed win over the Ospreys at the City Stadium.
Having won only one of their last seven matches in all competitions and had their their derby clash with the Newport Gwent Dragons called off earlier this week, this was a hugely important game for the Blues.
And they succeeded in bringing the Ospreys back down to earth after their record-equalling 60-17 thrashing of the Scarlets last Monday.
Tries from Tom James and Richard Mustoe put the Blues in control of this hotly-contested derby. They led 24-3 early in the second half, with influential fly-half Dan Parks kicking 14 of those points.
The Ospreys hit back with tries from Paul James, Tommy Bowe and Andrew Bishop but their fightback was not enough as they fell to just their second defeat in eight matches in all competitions.
An eager Cardiff side started brightly, hoping to take advantage of the fact that for the bulk of the Ospreys team this was their second game in four days.
Cardiff earned a penalty straight from the kick-off which Parks comfortably kicked from 25 yards. He added another penalty in the fifth minute, once again coming from a ruck infringement by the visitors.
The Blues were dominating territory and were happy to keep passing the ball in tight spaces, an ambition which earned reward when winger James went over on the left with full-back Chris Czekaj giving the scoring pass, following a break up the right by Casey Laulala.
Parks missed the conversion from wide out, while Ospreys number 10 Dan Biggar got his side on the scoreboard with a 45-yard penalty from a scrum. He would go on to miss two more long range efforts in the first half.
Parks put more points on the board to reward Cardiff's pressure as he slotted two drop goals to extend the lead to 17-3 at half-time.
The Ospreys needed to make something happen in the second half, but instead it was the Blues who extended their lead in the early stages following the sin-binning of props Paul James and Taufa'ao Filise.
Winger Mustoe injected a burst of pace and ran through unopposed for a try from 40 metres out, and Parks followed up with the extras to make it 24-3.
Belatedly, the Ospreys were stung into action and a lengthy period of attack in the Blues 22 eventually brought a reward when prop James forced his way over from short range after 60 minutes.
The Ospreys were given further hope when winger Bowe snatched an interception and went 50 yards for a try which was converted by James Hook.
The league's second-placed side then got back within a converted score when Hook added another penalty in the 69th minute, with both sides having replaced their starting fly-halves.
Ceri Sweeney, who came on for Parks, landed a penalty at the other end to give the Blues some extra breathing space and the kick proved crucial in the end.
Centre Bishop scored a late try for the Ospreys, converted by Hook, but it was only enough to earn a losing bonus point as the Blues held on for a victory that lifts them up to third in the table.