There is clear daylight at the top of the points table now with Coleg Sir Gar on 19 points while Coleg y Cymoedd and Llandovery College share second place with 10 points apiece.
Steffan Thomas got the Llanelli side under way on the 10th minute with a try but the lead was trimmed just three minutes later when Liam Free slotted a penalty.
Kieran Jones added a second try for the visitors in the 20th minute but again Cowbridge hit back, this time through a try by Nicky Griffiths which Free converted to level the score at 10-10.
Mitch Jones reclaimed the lead for Coleg Sir Gar with a penalty and right on the stroke of halftime Ioan Nicholas touched down to give the visitors a 10-18 lead at the break.
The second half was keenly contested and in the 55th minute Free converted his own try to leave his side just one point behind but 10 minutes later Delan Smith scored the vital try to secure the victory for Coleg Sir Gar.
Cup results
Bridgend College 17 – 10 Coleg Gwent
Coleg Y Cymoedd 36 – 17 Llandovery College
Cowbridge Comprehensive 17 – 23 Coleg Sir Gar
Trophy Results
Pembs Coll 41 – 25 Neath Port Talbot College
Newport High School 10 – 14 Gower College
