Heol y Cyw started the day in first place but lost for just the second time this season, going down 14-7 at Ystrad Rhondda. Rhys Truelove proved to be the difference between the teams, converting Adam Williams try and adding two penalties.
That was enough to cancel out Paul Songhurst's converted try. Ystrad Rhondda moved into second placed and Heol y Cyw slipped to third.
Treorchy made Gilfach Goch's day even worse as they moved above them in the table with a 14-11 triumph over Bedlinog. A penalty try and a converted effort from Craig Everett were enough to edge out the hosts.
In spite of a try from Martin Jones for the home side, converted by Ben Trzesicha, who also scored a penalty, Bedlinog remain bottom of the table while the Zebras move up to 10th.
One place above them in the table Rhydyfelin picked up a much needed win over Nelson with a narrow 21-20 victory. The visitors managed three tries through Kirk Claby, Ieuan Evans and Ross Bevin, but the boot of Ross Lucas saw Rhydyfelin home. He converted Marc Tyler and Gavin Close's tries as well as slotting over three penalties for his team as they won for the third time this season.
At the top end of the table fourth-place Rumney kept in touch with the league leaders as they comfortably saw off Penallta. Prop John Leadbetter and winger Lee Bendon scored tries while Danny Clarke added five points with the boot. The visitors remain stuck firmly in mid-table.
The final fixture of the day saw both sides score three tries each, but Ynysybwl managed to edge Glamorgan Wanderers by 19 points to 15. Nick Jones's two tries for the hosts weren't enough as the visitors kicked their way to victory at the Memorial Ground.