Cardiff clung on to claim a 9-16 win and a 17th consecutive BKT United Rugby Championship victory over the Dragons in a scrappy encounter at Rodney Parade.
The Blue and Blacks led by seven at half-time thanks to a long-range try from Mason Grady, on his first appearance since the World Cup.
Dragons battled back in a second-half, in which they dominated territory and possession, but they could not force the crucial score as Tinus de Beer edged Cardiff further in front.
Cardiff’s winning run over their nearest rivals stretches to 16 in all competitive fixtures or 17 in the league. The Blue and Blacks travel to face Scarlets in a second consecutive derby on the road next weekend.
Cardiff made a bright start at Rodney Parade with both Tomos Williams and Tinus de Beer utilising a short kicking game in attack to find space behind the Dragons rush.
It delivered early success with Cam Winnett and Mason Grady but on both occasions the blue and backs were unable to convert in heavy rain.
However, it was the Dragons that opened the scoring after winning a scrum penalty to kick down field and another penalty to allow O’Brien to boot the scoreboard into action.
The Dragons failed to secure the restart to allow Cardiff to go back on the attack. A long De Beer pass almost sent Cabango over and Tomos Williams wriggled over but he was held up. Cardiff were however playing with the advantage and De Beer levelled the scores 3-3 after 12 minutes.
The Blue and Blacks continued to play with tempo and chips over the top and they took the lead on 18 minutes thanks to the boot of De Beer.
Cardiff then came agonisingly close to snatching the game’s opening try. Off a poor Dragons box-kick De Beer sent a kick long into the left hand cover. Cabango won the race but the ball would n sit up, forcing him to grubber ahead.
It fell into the hands of Mason Grady and he offloaded out of contact back to Cabango but it was loose and under immense pressure the electric wing could not grasp possession.
The variety in attacking kicks from Williams and De Beer continued to cause the hosts problems, this time with a full-flight Grady soaring above Jordan Williams and bouncing him away. It took two more defenders to stop the centre before the Blue and Blacks went back to the right.
It looks as though they had the numbers but the Dragons scrambled well to stop Summerhill. Another attacking kick came from the base of the ruck but it evaded everyone as the Dragons survived once more. De Beer could have made it 3-9 as they returned for a penalty but he fired narrowly wide.
Momentum was beginning to turn in the Dragons’ favour as the 30 minute mark and with a vociferous home ground behind them their tales were up.
They looked to attack with their own chip on the edge of Cardiff’s twenty-two but Tomos Williams spotted the danger. He darted out of the line to charge the fly-half down and Teddy Williams collected.
The athletic second-row galloped forward and released Mason Grady, who raced 60 metres untouched to deliver a sucker punch try.
De Beer converted to leave Rodney Parade shellshocked but moments later it looked as though they had created a score of their own. On his opposite wing Jared Rosser broke clear and grubbered ahead. When De Beer lost control of the bobbling ball he crossed but play was brought back and they instead had to settle for a penalty, bringing the half-time score to 6-13.
Rosser had another opportunity to score shortly after the break, following a clever grubber to the corner, but he left the ball behind with the try-line at his mercy.
The Dragon remained camped the Cardiff half, with the home side now utilising their own short kicking game and the Blue and Blacks making early errors.
However, with the Dragons throwing everything at Cardiff, Liam Belcher delivered a captain’s turnover to relieve the pressure and De Beer cleared to the half-way line.
The tense, scrappy affair continued at pace but when Tomos Williams chipped over the top, de Beer chased and tackle and Thomas Young forced a turnover penalty, momentum swung once more.
De Beer misfired and the Dragons went back on the attack, hammering at the blue and black line.
The remained camped in the Cardiff half and bombarded the Blue and Blacks with high kicks to the corners. The pressure was telling but Theo Cabango displayed his class as he soared above multiple bodies to claim a swirling up and under, and then race clear. He beat one defender but was hauled down by the cover.
Cardiff continued to attack and eventually secured a penalty on the ten-metre line, which De Beer converted to settle the nerves. Dragons kicked out on the full from the restart with Cardiff now leading 6-16.
A late Dragons penalty took the home side to within a converted try, but the Blue and Blacks held out to take the victory.