Gilfach Goch's lead at the top of SWALEC Division Two East is down to just seven points after they crashed to a shock defeat at Mountain Ash.
The home side scored tries through scrum-half Meirion Thomas and lock Craig Locke, plus 10 points from the boot of fly-half Matthew Parfitt, as they beat their rivals and leapt to third place in the table with a 20-15 win.
Treorchy are now closing in on top spot after an easy victory at home to Ynysybwl, but missed out on the chance to narrow the gap further with their failure to secure the bonus point. The home side could only find the try line twice through Daniel John and Peter Hutchins as they sealed a 20-3 win.
Llantrisant almost certainly sealed their survival with a moral-boosting triumph at home to Garndiffaith. A Gareth Thomas double and one from Gavin Jones saw them cruise to a 28-8 victory.
Abergavenny are still well clear at the top of Division Three East, but they were pushed all the way by a spirited performance by lowly Gwernyfed. Hooker Craig Fuller scored for the home side but it wasn't enough as the league leaders hit back through wing Ian Davies and eight points from Dan Hayman's boot to scrape home, 13-5.
Fleur de Lys are still 12 points off the top after leaving it late to beat Tredegar Ironsides, but they do have four games in hand on the leaders. The Ironsides took a first half lead through a try by lock Lewis Jones.
But Fleur de Lys talisman Paul Emanuelli reduced the gap with a penalty, before knocking over another to win it 6-5 in the 70th minute.
Bottom side Cwmbran turned in a spectacular performance to demolish Blaina 45-19 and give their survival bid a glimmer of hope. Full-back Carl Moore and centre Gareth Roberts registered a double-apiece and Ian Hayes and Nicky Witts also crossed as Cwbran claimed the bonus point and closed the gap on the teams above them to eight points.
Elsewhere there was a shock 29-7 victory for Newport HSOB at Nelson and Rhymney kept up their promotion push with a 26-18 win at Croesyceiliog.
Nearly 40 players were involved in the first Wales Under 18 training session of the season. WRU National Performance Manager Gethin Watts is excited at the potential shown by the group and expects the Regional Under 18 Championship to hone their skills even further.