Lloyd banged over six goals in atrocious conditions at the Groe as the Bulls shrugged off an early 19-0 deficit to beat the table-toppers 26-22. Forwards Ben Duggan and Gareth Kinsey scored second-half tries for the home side.
Team manager Justin Lewis said the victory was perfect preparation for his side's Konica Minolta Cup quarter-final match at Pontypridd next Saturday.
"We were 19-0 down after only 10 minutes, but we had chosen to play into the wind in the first half and that paid off," he said.
"It wasn't a day for the backs, so in the second half, we knew we had to keep it in the forwards and keep driving it up the middle. We've missed Rob Lloyd for the last three games, because he's a Marine and he's been away, and his kicking was crucial.
"We said before the game that we could win this one, and we knew it would give us a lot of confidence ahead of playing a Premiership side at Sardis Road.
"This season is strange - we can produce this sort of performance against the good sides, but can't seem to do it against the poorer sides."
Despite the loss, Bonymaen are still warm favourites to finish on top of the league. Their nearest rivals, Beddau, had a royal chance to narrow the margin to two points but crashed 31-13 at home to fellow title contenders Newbridge.
In another game decided by the wind, Beddau led 13-11 at the break, only to concede second-half tries to forwards Chris James and Chris Payne. Newbridge outside-half Greg Jones added 16 points with the boot.
Cwmllynfell continued their fine season with a 23-15 win at Caerphilly, with Neil Thomas, Paul Davies and Jim Morgan scoring tries for the visitors, while Merthyr ran in five first-half tries in their 27-10 victory over Narberth.
Waunarlwydd shut out Fleur de Lys 15-0, with a try double to Ed Bennett, and Blackwood found their feet in the second half to come back and beat Llanharan 20-15.
Fourth-placed Whitland spurned a chance to climb the table when their home match against bottom-placed Ystrad Rhondda finished in a rare nil-all draw. The mid-table Llangennech-UWIC match was abandoned at halftime because of torrential rain. Llangennech were leading 7-5 at the time.
The SWALEC semi-final draws threw up some mouth-watering clashes in the Cup, Plate and Bowl as the 12 teams aim for the Millennium Stadium Finals Day. All the semi-finals are to be played on the weekend of April 12.
Welsh whistler Rhys Thomas continues to scale the heights of the game as he prepares to be an official in this weekend's Hong Kong Sevens tournament, undoubtedly the showpiece event on the World Series calendar.
Wales International Ian Evans and Wales and Lions legend Scott Quinnell swapped rugby balls for paint pots at Tonna during the RBS 6 Nations. They surprised club players with a special clubhouse makeover to launch NatWest RugbyForce 2014 - a programme developed in partnership with the WRU to make rugby clubs stronger businesses by improving and renovating their facilities with the support of volunteers and the local community.
Fresh from claiming the Bowl honours in Tokyo last Sunday, the Wales Sevens squad have settled into their routine as they prepare for this weekend's Hong Kong tournament where Iolo Evans is aiming high, as WRU TV's Graeme Gillespie discovers.
The Welsh Rugby Union has recently teamed up with Prostate Cymru to help the charity launch its latest campaign to raise awareness of the disease. Members of the Wales squad helped produce a short video and promotional material for the campaign titled 'The Best Defence - is to know the FACTS'.
Defending champions Coleg Sir Gar reached their second consecutive Millennium Stadium final as they defeated Coleg Gwent in the WRU Wednesday Under 18 play-off. Watch highlights of their narrow 10-8 win here.