AN astonishing burst of scoring in the second half by Cardiff Blues left Newport Gwent Dragons shattered in last night’s Magners League Welsh derby at the Cardiff City Stadium.

The Dragons, without half-a-dozen leading players, rocked the Blues by storming into a 13-3 half-time lead, but the hosts completely transformed the picture after the interval.

They shot out of the blocks and scored 27 unanswered points in only 24 minutes to wrap up victory. A bonus point try followed, plus another one, as they narrowed the gap on the Dragons in the league to three points.

But the Dragons remain nine points in front of the Scarlets and the New Year’s Eve clash between the east-west rivals at Rodney Parade will be pivotal in the battle for a top three place among the Welsh teams.

The Dragons suffered another major injury blow before the game when back row forward Joe Bearman withdrew with a stomach muscle problem having only just returned from more than two months out with groin trouble.

He joined Ashley Smith, Wayne Evans, Ben Castle, Nigel Hall, Luke Charteris and Dan Lydiate as leading players on the sidelines.

And it quickly got worse when the Dragons fell behind to a fourth minute penalty by Ben Blair for a scrum offence after the full back had struck an upright with a much harder attempt two minutes earlier.

Opposite number Jason Tovey was well wide with a penalty attempt for the Dragons, but they shook the Blues by storming ahead with a super try after 12 minutes.

And it came from a pretty unpromising situation after Rhodri Davies was hurled back in the tackle. But lock Rob Sidoli scrambled the ball back between his legs and prop Hugh Gustafson set off down field before putting Aled Brew away with a nicely timed pass and the wing put his head back and shot away on a 30-yard run for a try which James Arlidge converted, the ball going over via an upright.

Almost immediately scrum half Danny Lee threatened with a piercing run from a scrum and when he chipped for the corner Blair had to scamper back to cover with Arlidge challenging.

The Dragons lost a golden opportunity to increase their lead when Arlidge missed an easy penalty attempt after his chip through resulted in the clearest yellow card offence you will ever see when Blues hooker Rhys Thomas dived on the ball in an offside position.

But the seven-man home pack shunted the Dragons pack backwards only for sloppy handling by the backs to let them down.

The Dragons continued to make the running and they almost got their second try after lock Hoani MacDonald ploughed around the front of a line-out and the pack piled in, but Richard Fussell was well policed when he tried to break through.

The Dragons lost Davies who looked groggy after being involved in several heavy tackles, replaced by Matthew Watkins, but it made no difference as Arlidge made up for his earlier miss by landing a penalty to stretch his side’s lead to seven points.

The Blues swarmed upfield and were brought back up to full strength just in time for a scrum near the Dragons’ line only for Sam Warburton to knock on.

Arlidge missed a long range penalty shot, but with the last kick of the half Jason Tovey gathered a stray clearance by Sam Norton-Knight and with plenty of time carefully took aim and slammed over a dropped goal almost from halfway to give the Dragons an undreamed of 13-3 half-time lead.

But they had flattered to deceive and within five minutes of the restart the Blues were level. Blair kicked his second penalty and after the defence was caught at sixes and sevens Xavier Rush drove from a scrum and lock Bradley Davies plunged over for a try which Blair converted.

And they took the lead when Blair landed a sitter after the Dragons backs were caught offside. But The Dragons were unlucky not to regain the lead when wing Richard Fussell chipped ahead, regathered and was away only to be recalled for a push on Blair.

But the luck evened itself out when Tom James finished off a fine handling move to cross in the left corner only for the TMO to deny him a try because the Blues wing lost the ball in the act of touching down.

But they made certain moments later when no one got under a Norton-Knight kick and ex-Dragons wing Richard Mustoe picked the ball up and strolled over for a try which Blair converted.

It was rapidly turning into a rout and the Blues scored their third try when Rees broke through a tackle by Gavin Thomas to score with ease, Blair converting.

The Dragons were further hit when Brew got himself yellow carded for the second game running, again for an illegal challenge.

And the Blues took advantage with their bonus point try when Tom Shanklin broke through to cross, Blair converting to take his match haul to 17 points.

There was still time for James to be on the end of a bout of handling by the Blues to scorch over in the corner for their fifth try.

Cardiff Blues: B Blair, R Mustoe, T Shanklin, J Roberts (G Thomas 64), T James, S Norton-Knight (C Sweeney 75), R Rees (G Cooper 76), G Jenkins (captain), R Thomas (R Williams 76), T Filise (G Powell 73), B Davies, S Morgan (P Tito 75), S Warburton (R Williams 34-39), X Rush, M Williams (A Powell 75).

Scorers -- tries: B Davies, R Mustoe, R Rees, T Shanklin, T James; conversions: B Blair (4); penalties: Blair (3).

Newport Gwent Dragons: J Tovey, A Brew, R Davies (M Watkins 31-40, 45), T Riley, R Fussell, J Arlidge (W Harries 60), D Lee (G Williams 67), H Gustafson, T Willis, captain (S Jones 64), P Palmer (P Bracken 74), H MacDonald (A Jones 64), R Sidoli, G Webb, L Evans, G Thomas (J Harris 75).

Scorers -- try: A Brew; conversion: Arlidge; penalty: J Arlidge; dropped goal: J Tovey.

Referee: James Jones (WRU).

Attendance: 15,210.