Monmouth entertained Blackwood Stars and within three minutes of the start, the visitors were left shaking their heads to be seven points behind thanks to a dazzling set-piece move by Gareth Morgan, who ran flat from the base of a scrum before finding a gap to cut through on the right.
Fly-half Rhys Ricketts, who scored 16 points and won the inaugural Gareth Davies Man of the Match award, converted. Blackwood immediately struck back, possibly with the aid of an unobserved knock on, to score five points.
Monmouth were adjudged to be offside at a defensive ruck and the visitors took the lead five-eight.
Left wing Jack Butler was next to score on the rebound to take the lead again, although Ricketts found the angle too difficult. A missed tackle in the centre allowed Blackwood to regain the lead 12-13.