Coleg Morgannwg defeated Pembs College 52-0 after leading 19-0 at the break with prop Calum Lewis, centre Jack Morris and No 8 Lewis Young scoring tries.
The second half saw Morgannwg take firm control up front with skipper Young always to the fore.
Five more tries came at regular intervals through hooker Jack Dando, lock Alwyn Lee, wing Jack Barrett plus flanker Jack Perkins and Morris again.
Fly-half Garin Thomas kicked six conversions out of eight to set the seal on a hugely promising start for the college.
Coleg Sir Gar brushed aside the challenge of Bridgend College with a comfortable 40-9 triumph.
Led by their quick and elusive full-back Luke Treharne, Coleg Sir Gâr were in control from first to last, scoring three tries in each half to post notice that they will be the side to beat in the league.
Not that Bridgend were outclassed but they suffered badly from a lack of possession and were it not for some brave tackling in the last quarter, they would have shipped far more points.
With prop Samson Lee, lock Curtis Morris and flanker Jake Iles prominent in tight and loose, CSG were soon 12-0 ahead with a try apiece from their two main attackers – the darting Treharne and intuitive fly-half Jordan Williams.
Williams added the conversion of his own try before the visitors fly-half Corey Butler kicked two penalties.
Treharne got another converted try only for Butler to keep Bridgend in touch with his third penalty but it was very much one way traffic thereafter.
Skipper and lock Matt Screech, flanker David Griggs and hooker Evan Yardley worked overtime for the visitors but converted tries from Williams, lock Jake Simm and wing Aaron Evans ensured a maximum five point haul for the home side.
Gower College were good value for their 17-7 win over Neath Port Talbot College.
In the all Ospreys clash, they built up a solid 17-0 half-time lead thanks to the good work of their pack in which No 8 Rhys Leonard, hooker Scott Otten and lock Rhodri Hughes were the leading lights.
Flanker Alun Rees and scrum-half Will Batcup got the tries and Davies – son of Scarlets coach Nigel Davies – added the conversions and two penalties.
The wind and drizzle at St Helen’s made for a scrappy second-half but the sterling efforts of No 8 Matt Jenkins, wing Nathan Brooks and full-back Rhys Williams brought NPT right back into the game.
They got a try from the non-stop Jenkins, converted by busy scrum-half Rhodri Coles but then squandered a golden try opportunity before the game petered out amongst a raft of substitutions.
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