Penarth are out of the WRU Division One Cup following a 16-13 defeat at Aberavon Green Stars in the quarter finals.
The Bears were ahead by just one point at the break amid tough muddy conditions at the Pavilion Ground in Port Talbot on Saturday
Harry Williams and Osian Coates crossed for the visitors with Rhys Mottram adding a penalty but missing both conversions as the hosts edged past to book their place in the semis.
Penarth remain top of Division One East Central - and resume their Admiral League title campaign next Saturday when they entertain struggling Cambrian Welfare at the Athletic Ground.
Elsewhere, the Division Two Cup quarter final between Cowbridge and Clwb Rygbi Cymry Caerdydd was postponed due to a waterlogged pitch.
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