Having trailed 13-0 mid-way through the first half, the hosts recovered to lead 15-13 at half time courtesy of tries from centre Hallom Amos and wing Ashton Hewitt and a conversion and penalty from outside half Lloyd Rogers.
Geraint Llewellyn, who kicked two penalties and converted his own try before the interval, edged the South back in front with a penalty in the early stages of the second period, before the Dragons struck back with a winning try, five minutes from full time, by full-back and captain Mitchell Starr.
Although the Dragons found themselves down to 13 men in the second half when prop Luke Garrett and lock Derryn Jones were yellow carded, assistant team manager Colin Brennan said his side were good value for their opening night success.
“We had to hang in there when we lost the two forwards, but to the team’s credit, they did exactly that and were deserving of the win,” said Brennan.
Last season’s Under 16 finalists, the Ospreys and Scarlets, met at Parc y Scarlets with the visitors coming out on top 28-15 courtesy of two tries from wing Dafydd Howells and one apiece from centre Joe Thomas and wing Alex Bidwell.
Outside half Josh White kicked four conversions for good measure as the Ospreys made a winning start to their season.
In a one-sided first half, the visitors used the wind to establish themselves against a plucky Scarlets side who were far from overawed by their hosts.
After the break and with the elements in their favour, the Scarlets got back to 21-15 thanks to tries from wing Matthew Davies and No.8 Lee Taylor and a penalty and conversion from Jack Maynard.
However, the Ospreys finished with a bang and made sure of the points when Howells nipped in for his second try that White converted.
The Scarlets Under 18s were too strong for the Ospreys at Llandarcy, winning 36-16 courtesy of 26 points from Jordan Williams. The outstanding outside half, who starred for the region in last last season’s Under 16 competition, scored two tries before half time with half back partner Rhodri Williams crossing for a third.
Williams, the pivot, completed his hat trick as the Scarlets made sure while Jake Randell added a fifth late on. Williams kicked four conversions and a penalty while for the Ospreys, who trailed 22-15 at half-time, there was a try from Ashley Evans and 11 points from the boot of outside half Sam Davies.
