Cross Keys held off a determined challenge from Llanharan, who led 12-8 at halfway before the Keys came out 37-27 winners.
Keys tries came from scrum half Gareth Betts, lock Grant Wilson, fly half Owen Biddiscombe, No 8 Rhys Williams and centre Daniel Dark with Darren Miles kicking three conversions and two penalties. Llanharan notched foour tries from hooker Alyn Williams, scrum half Jonathan Hooper, prop Gareth Edwards and centre John Leyshon with Marc Davies placing two conversions and a penalty.
Bridgend took their unbeaten cup and league run to 11 matches by winning 33-20 at Ebbw Vale after racing clear at 27-10 in the first half. Gareth David placed three penalties and converted tries by centre Chris Tossell, wing Gareth Epton and centre Ryan Howells, while Jason Williams scored a try, two conversions and two penalties and Rhys Bowen added a try for Ebbw Vale.
Cardiff travelled to West Wales to defeat Llandovery 35-13 and will be on the road again on Saturday when they visit Carmarthen in the Konica Minolta Cup. Their speedy backs produced three of their five tries eith Liam Roberts grabbing two and Elgan Jones one, while Michael Leaman also crossed and there was a penalty try with Chris Anderson goaling them all.
For the Drovers, centre Gary Beaumont-Morgan crossed for a try and Simon Daniel, on loan again from Waunarlwydd, kicked eight points.
Caerphilly moved from penultimate place in the division above Llanharan after scoring four tries in a 22-8 beating of Bedwas at Virginia Park. Wing Mike Silcox (2), flanker Andy Edwards asnd centre Hustin Thomas were the try-scorers with a Nick Thomas conversion, while Dan Jones scored a try and Andrew James a penalty for Bedwas.