The defeat could have been more damaging, but Pontypridd, who are snapping at their heels in the league, also lost against bottom of the table Treorchy.
On the other hand, Tommy David, the ex-British Lion and rugby league player who has taken over as rugby director of Newport and directed his first training session on Thursday, was delighted at this turn-up for his side.
Newport scored the only try and stuck to their guns throughout. The veteran Kevin Moseley and Richard Goodey won the ball in the line-out, Jason Hewlett snapped at the heels of the forwards and Gareth Rees kicked majestically at stand-off. Newport never allowed Cardiff into the game.
Considering the traditional rivalry of these famous protagonists, there was precious little passion on show, but then few of the players were either Cardiff or Newport born and bred, which is the new order of things.
There were, in fact, three ex-Cardiff players in the Newport back division, and one sensed they were playing more for league points than pride. And not doing it very well, it must be said, for the game was a grim sequence of handling errors compounded by a referee who seemed to enjoy blowing his whistle and made no concession to the idea of playing advantage.
The crucial Newport score came after three minutes when Hewlett, who won the man of the match award, made the only try of the game by kicking through. When Andrew Booth failed to kick into touch, the scrum-half chipped the ball into the hands of Owain Thomas, who scored in the corner. Gareth Rees supplied the conversion.
The match was settled with six penalty goals for Cardiff by Chris John and five for Newport by Gareth Rees. There were 16 penalty kicks in all - unfortunately it was that kind of game.
Cardiff: C John; N Walker, S John, M Hall (capt), S Hill; M Ring, A Booth; A Lewis, P Young, M Griffiths, J Wakeford, K Stewart, O Williams, E Lewis, C Mills.
Newport: S Davies; R Rees, D Hughes, D Edwards, O Thomas; G Rees, J Hewlett; S Duggan, A Peacock, S Cronk, N Jones, K Moseley, M Workman, R Goodey (capt), D Gray.
Referee: D R Davies (WRU).