Warriors suffered their first injury setback when Canadian international prop Kevin Tkachuk was forced off with a shoulder problem. And it was only after the departure of Petrie that the encounter started to produce fluent and attacking rugby.
Within just two minutes of the bust-up, Glasgow at last found half a gap in the Dragons' line of markers and flanker Steve Swindall bullocked his way under the crossbar to give Parks a formality of a conversion. Glasgow maintained the momentum, but were unable to add to their tally before the interval.
Dragons came out with much more purpose after the restart and a spell of intense pressure paved the way for their equalising score. Winger Richard Fussell had set up the position with a long and mazy run before captain Jason Forster burrowed through from point-blank range. Craig Warlow added the extras from a tricky angle.
And the visitors surged ahead with a touchdown by Gareth Wyatt following an interception on the halfway line. Again Warlow was on-target from wide. Parks clawed back a penalty to set up an exciting finale in which Richard Bryan pounced on a loose ball to make sure for Newport, Warlow converting. There was still time for Mike Roberts to mark his Glasgow debut with a consolation try.