Corus recorded their fifth straight win with a 29-22 result in an entertaining, seven-try match against Kidwelly. Lewis scored two tries and kicked nine points as the league leaders kept their noses ahead of Dunvant, who made it four out of four with an impressive 30-3 win at Carmarthen Athletic.
Gorseinon were the only other team who went into Saturday's games with an unbeaten record, but Bridgend Athletic took care of that with a well-deserved 20-13 win at home.
Seven Sisters fullback Kevin Lewis kicked four penalty goals as his side edged past Felinfoel 22-14 to record their second victory of the season. Loughor fullback Lee Davis matched Lewis' feat, his four goals providing all of his side's points in their 12-10 win at winless Banwen, while Maesteg Quins beat Tonmawr 17-3 and Pontyberem accounted for Mumbles 20-12.
Trimsaran and Haverfordwest are locked together at the top of Division 3 West, although Haverfordwest did it the hard way with an 18-16 win at winless Lampeter. Trimsaran cruised to a comfortable 27-3 victory over Newcastle Emlyn.
At the wrong end of the table, Tumble (35-19 losers to Aberystwyth), Lampeter and Hendy (18-5 losers to Tenby) are still looking to lose the duck's egg beside their names.
In Division 4 West, Pontarddulais continue on their merry way at the top after a 37-6 win at Cardigan, while second-placed Neyland were held to a 13-all draw at Milford. There was another draw in the division, with bottom-placed Llandybie earning their first point of the season courtesy of a 6-all deadlock at home to mid-table Ammanford.
Llanybydder are alone at the top of Division 5 West after their fifth straight victory - a 49-0 mauling of Pontyates - although Burry Port also retained unbeaten with a gritty 22-18 victory at Tycroes.
Pontyates are one of three sides still looking for their first win. The two Saints - David and Clears - are holding up the table after St Davids fans had to sit through a 57-6 hammering at the hands of Gowerton and St Clears fell 16-36 at home to a Llangwm side celebrating their first win of the season.
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.