"It was a pure accident. Brett was playing at full back and dropped on a ball that had been fly kicked through," explained Beddau chairman Lyn West. "It was a typically brave piece of play by Brett and he caught a boot on his lower leg as the Merthyr player tried to hack on the ball.
"It's a bitter blow for us because Brett is such an inspirational figure at the club. He's a great influence on the coaching side and is our main man on the field.
"I doubt we will see him playing again for us this season and this injury must raise a question mark over whether he will play again."
Davey provided all of Beddau's first-half points as he stroked over two penalties, but Merthyr were in the driving seat by half-time as they led 13-6. A strong pack performance for the visitors saw them claim a penalty try, another from No. 8 Jason Price and a third from full-back Luke Jones. Outside half Neil Bennett added 18 points with his boot.
Beddau's first defeat of the season, along with those of Cmwllynfell and Newbridge, mean Bonymaen are the only undefeated team in the division. Their 46-10 win at Fleur de Lys moved them to the top of the table.
Wings Jason Wride and Chris Batsford both grabbed two tries each as the Swansea side ran in seven to stun the home side and leave them firmly anchored to the bottom of the table. Fleur's one highlight was a try from a rolling maul by former Newport and Wales back row man Glenn George.
The two other unbeaten records that fell were at Ystrad Rhondda, where league leaders Cwmllynfell were beaten 34-27 and at Newbridge, where Narberth ran out 29-16 victors. Ystrad hit back strongly after two successive defeats to outscore their high-flying visitors by four tries to three in the match of the day. The steadying influence of new recruit Jason Lewis at centre was vital in the home side's back division and wing Dai John bagged two tries and full back Mark Davies got another. Lock Lee Blowers, who scored for a second weekend in a row, opened the scoring and Dylan Jones converted all four tries and added two penalties to complete a superb victory.
Narberth were too strong for Newbridge at the Welfare Ground, outscoring their hosts by four tries to two. An even first-half, in which Greg Callow kicked two penalties for Newbridge and wing Mark Davies crossed for a Narberth try that Rob Irving converted, was followed by a brisk bout of scoring at the start of the second half that saw the visitors stretch their lead to 26-11 before Martin Ackerman grabbed a consolation try for the home side at the death.
There were 13 tries in a 92 match thriller at UWIC, where the students handed out a lesson in finishing to Llanharan. Full back Martin Thomas marked his debut with two of the nine home tries in a stunning 60-32 win and wing George Dixon also got a brace. Lock Fatita Molitika made it three tries in two games with one of Llanharan's four tires. Wayne Jervis chipped in with 15 points from the boot.
Builth Wells had Rob Lloyd to thank for their first win of the season as he scored all the points in a 16-14 victory at Waunarlwydd. With the game still scorelss at half-time, Lloyd moved from full back to outside half and went through the score card with a try, conversion, two penalties and a drop goal.
Whitland flanker Phil Morgan got a hat-trick of tries as the Pembrokeshire club heaped more misery on Caerphilly in a 45-3 home win. Eifion Roberts and Ryan Michael got further home tries and Aled Davies kicked 15 points.
Llanegennech's young back division, superbly marshalled by last season's youth team outside half Ellis Phillips, gave Blackwood the run around in a 38-6 home win. There were five tries without reply for the home side and Phillips added to his mounting reputation by converting them all and adding a penalty.