Fourteen-man Dragons Under-18s kicked off the new Regional Age Grade Championship with a 27-10 defeat to Cardiff Blues at Ystrad Mynach on Tuesday evening.
Wales Under-18 wing Carrick McDonough grabbed a second half try to cut the visitors lead to 12-10 just after the break.
But tries from Efan Daniel and Ryan Wilkins – to add to earlier scores from Iestyn Galton and Cai James – saw Blues run out winners.
Dragons, who were captained by back row Lewis Stansfield, had to finish the game with 14 men after wing Morgan Mohring received his second yellow card for a deliberate knock-on.
Fly half Joe Westwood scored the other points on the night with a first half penalty and conversion.
Dragons Under-18s are next in action on Wednesday (September 4) when they tackle Ospreys Under-18s at Port Talbot (kick-off 7.15pm).
23m Westwood p 3-0
27m Galton t 3-5
41m James t Burnell c 3-12
44m McDonough t Westwood c 10-12
46m Daniel t Burnell c 10-19
53m Burnell p 10-22
56m Wilkins t 10-27
Dragons Under-18s: Evan Gregg, Carrick McDonough, Jonny Paynter (Andrews 36), Oli Andrew (Brian 55), Morgan Mohring, Joe Westwood, Che Hope (Lloyd 55); Aaron Dowse (Strachan 68), Conor Chapman (Smith 68), Lui Hewlett (Powell 55), George Young, Joe Peard (Langdon 41), Lewis Stansfield (Thomas 55), Joe Coope-Franklin, Ben Moa
Replacements: Pacey Smith, Jamie Strachan, Jack Powell, Ben Langdon, Ollie Thomas, Morgan Lloyd, Oliver Brian, Oli Andrews