Inevitably, there was little festive spirit about the opening exchanges with both sides hurling themselves into the physical encounters and a string of penalties resulting.

Blues full-back Ben Blair landed the first after just two minutes, Ospreys responding through fly-half Dan Biggar, and both players missed further kicks before Blair restored his side's lead.

A rampaging run by centre Sonny Parker threatened the first try for the Ospreys, but the move broke down when flanker Marty Holah opted for a grubber kick in the home 22 rather than keeping the ball in hand.

The visitors wasted a further opportunity when 19-year-old Biggar slung out a wild pass. Gavin Henson, playing at full-back, did well to retrieve it, but was isolated and conceded a penalty.

Young Biggar played a key role when the Ospreys finally crossed the line just after the half-hour. His agility and sleight of hand kept the ball alive before Tommy Bowe fed Lee Byrne and the Wales No 15, in a rare outing on the wing, stepped inside flanker Maama Molitika to touch down.

The Blues' own prodigy, 20-year-old Leigh Halfpenny, on for the injured Blair, raced through the visitors' defence on a 50-yard gallop but lost his footing just short of the try line. A drop goal by Nicky Robinson ensured his good work did not go totally unrewarded and gave the home side a narrow half-time lead.

Both sides missed early penalties in the second period before the Ospreys threw down the gauntlet by bringing on Wales fly-half James Hock to replace Biggar.

It was the Blues who scored next, however, after a remarkable 60-yard break by Tom James had been ended illegally by Byrne, who received a yellow card while Robinson slotted over the penalty.

A long-range kick by Hock kept the Ospreys in touch and it needed two despairing tackles by Halfpenny to save the day as the visitors threw themselves into the search for a winning score.

Their sustained pressure was rewarded with barely five minutes left, a superb long pass from Hock finding Tiatia on the left to dive over.

Despite all their last-ditch efforts, the Blues were unable to respond and the Ospreys underlined their status as the best team in Wales.