Bridgend survived the sin-binning of their entire front-row in the second half to record a 31-10 win over Pontypridd at the Brewery Field.
Props Gareth Alexander and Tom Hearne and hooker Ieuan Dobbs all earned 10-minute spells in the bin, but late tries from Gareth Williams and Andrew Joy gave the Ravens a valuable win.
In the upset of the day, bottom-placed Llandovery recorded only their second win of the season - a 37-0 result at home to Ebbw Vale.
In re-scheduled Konica Minolta Cup matches, Premiership side Glamorgan Wanderers demolished Ystrad Rhondda 62-0, with Geoff Hobbs running in a hat-trick of tries, and Cross Keys pipped fellow Premiership club Bedwas 20-19. Bedwas scored in the last minute to make it a one-point ballgame, but the conversion attempt hit an upright and bounced out.
Premier Division results: Bridgend 31 Pontypridd 10, Cardiff 25 Maesteg 34, Llandovery 37 Ebbw Vale 0, Swansea 29 Pontypool 45.
Konica Minolta Cup, round 3: Glamorgan Wanderers 62 Ystrad Rhondda 0, Cross Keys 20 Bedwas 19.