The Carmarthen centre Aled Thomas broke his right leg and the referee call an end to proceedings while he was carefully taken off the field. At that stage the home side Glynneath, were leading 23-13.
Meanwhile, Tondu made it five wins from five after thrashing bottom placed Aberavon Quins 57-0. No 8 Matt Phillips scored two tries while Paul Smith contributed 15 points for the home side, including six conversions.
Quins are still searching for their first point and will play Ammanford, who defeated Waunarlwydd 30-23, next time out on the league.
In other results in Division 1, Cwmllynfell have moved up into second place with a comfortable 28-13 home win against Loughor.
Tries from Sean Burnell, Tyrone Maffey, Ashley Hickie and Steven Gillard was enough to give Kenfig Hill their third consecutive win after defeating Llangennech 23-19, who now have lost two on the spin.
In Division 2, Maesteg’s impressive unbeaten start continues with a 28-23 home victory over Dunvant. The home side’s failure to win with a bonus point was the only downside as that allowed Seven Sisters and Builth Wells to close the gap at the top to three points after both sides were winners of their games with four or more tries.
Builth Wells scored seven tries with a 50-0 hammering at home of Haverfordwest while Seven Sisters won narrowly against Felinfoel 29-22.
Amman United remains top of Division three, despite losing their 100 percent record in a 20-6 defeat against a Tenby United side which has escalated to third place.
Amman United’s defeat means that there is now a two point gap between the top five. Newcastle Emlyn are second place having beaten fifth place Gorseinon 43-14 whilst Pontardulais occupy fourth spot with a 24-15 away win against Cardigan.
The only result in Division 4 saw Llanybydder rise to second place behind Tycroes, having overcome previously unbeaten Trimsaran with a 38-15 bonus point victory.