Cardiff Blues battled back to secure the Boxing Day derby bragging rights with scrappy victory at Rodney Parade.
The capital city outfit went into the encounter on the back of 10 consecutive Guinness PRO14 victories over their nearest rivals.
They trailed for the majority of the encounter following an indisciplined start that handed the hosts a nine-point head start.
However, after displaying an abundance of grit and determination in difficult conditions, Josh Turnbull powered over for the decisive try.
Evans converted to give Cardiff Blues the most slender of leads before a Guinness Player of the Match, James Botham, was harshly denied his first try of the season in the final moments.
Despite a bring start, a succession of penalties awarded to the Dragons put the hosts on the front foot and Josh Lewis opened the scoring from the 22.
The Dragons continued to benefit from marginal decisions awarded in their favour with a 5-1 penalty count to the favour of Dean Ryan’s side after little more than 10 minutes.
That meant while also playing into a driving wind, Cardiff were pinned in their own half and left to play of scraps. Another penalty awarded to the Dragons, which left Wales’ Capital Region baffled, saw Lewis make it 6-0.
The indiscipline continued and the Dragons were soon awarded a seventh consecutive penalty, which Lewis slotted for a 9-0 lead.
When finally awarded a penalty of their own, Cardiff Blues built into the game with a rampaging driving lineout. A snipe down the blind set set Dragons alarm bells ringing and Matthew Screech took the scrum-half out from an illegal position.
Evans put the ball in the corner and following plenty of forward grunt, the pack powered over the whitewash. However following a long debate between Evans and assistant referee Nigel Owens, then an eternity of video replays it was adjudged the ball had been stripped just as Kristian Dacey stretched out to ground.
Cardiff Blues were awarded a free kick and opted for the scrum but yet again Evans blew his whistle to give the Dragons a reprieve.
However, it was now Cardiff Blues that turned the screw and benefitted from a number of penalties as they kept it tight and hit up with their big men.
One penalty kicked to the corner was lost but on 32 minutes Jarrod Evans slotted his first points of the evening to make it 9-3.
Lewis booted the scoreboard back into action on 45 minutes to restore the Dragons nine-point advantage.
Following a sustained period of pressure, Evans knocked over his second to make it 12-6 and as the scrappy encounter progressed Cardiff Blues enjoyed more territory and possession.
They turned down at least two shots at goal but finally had their reward when Turnbull powered over from close range following another relentless spell of pressure.
Evans added the simple conversion to give his side the lead for the first time. The tide continued to turn as the Dragons kicked a penalty dead and Cardiff continued to turn the screw at the set-piece.
The Blues were twice held agonisingly short with driving lineouts in the final minutes but remained camped on the Dragons five-metre line, with Botham convinced he had touched down, but the TMO disagreeing.
However, the visitors remained in control in the final moments and dominated both possession and territory to kick off the festive period with four points.