Bonymaen shocked Carmarthen Athletic to win 14-13 at Five Fields and move off the bottom of Division One West.
Winger Robert Jones scored Bonymaen's only try, with Richard Cunniffe kicking their other nine points with two penalties and a drop goal.
Town rivals Carmarthen Quins faired much better, winning 32-6 at Cwmllynfell to extend their unbeaten run and remain top of the table.
In light of Bonymaen's win, Dunvant are now eight points adrift at the foot of the table following their 75-0 thrashing at second-place Tonmawr.
The Pitmen ran in 13 tries, with Ryan Baylis standing out as their hat-trick hero. He crossed three times during an emphatic victory, with Ben Davies going over twice as one of nine other Tonmawr try-scorers.
Whitland moved third after beating Llangennech 45-3, posting six tries including two for Lee Glanville.
Corus ran in four tries to beat Narberth 34-10, with full-back Rhys Williams kicking 11 points for the Steelmen. Felinfoel change places with Maesteg in sixth after they won 19-18 at Llynfi Road.
Merthyr stay top of Division One East with a predictable sixth victory of the camapign at bottom side Newport Saracens, who remain without a win so far this season. Full-back Adam Williams scored two of his team's six tries in the comfortable 43-7 win.
Newbridge remain second following their 33-16 success against Llanharan following two tries from Ceri Young.
Bargoed racked up a bonus point in their impressive 30-5 away win at Penallta keeping them hot on the trail of the top two.
Beddau lifted themselves clear of relegation with a 41-16 victory over Rumney. Matthew Evans scored two tries for Beaddau, the others came from Slater, Cleverly and Adams while Rhys Truelove racked up an impressive 16 points from the boot.
Gareth Price kicked three penalties to secure a 14-10 win for Blackwood over strugglers Ystrad Rhondda while Uwic scored four tries to beat Caerhilly 29-23 in a thrilling game at Virginia Park. Uwic held a convincing 17-5 lead at half-time but were left holding on at the end thanks to some reliable kicking from the boot of Colin Ashton.
Carmarthen Quins are holding an exhibition to commemorate club players who fought in World War I. All welcome to the clubhouse on Friday afternoon to learn more about local history, or share any family anecdotes or artifacts.
Defence coach Shaun Edwards believes Saturday's clash against England - the 'form team in world rugby' - poses a huge challenge for his side but he is confident, with Wales beginning to show the defensive qualities displayed in the last two World Cups,