A tough first-half saw the home side lead 10-6 thanks to tries form Darren Witcomb and Adam Hoskins, but no sooner had the second-half started than Blaenavon edged ahead 11-10 with a try from the kick-off.
With the wind at their backs Brecon unleashed a fiercesome fightback that saw skipper and No 8 Ewan Williams, scrum half Deri Williams, prop Richard Davies, wing Lucas Jones and lock Mark Squirrell add further tries. Dean Gunter, who joined full time from Merthyr in the summer, converted two and kicked a penalty.
Brynmawr, who 26-15 home winners over Dowlais, and Ynysbwl, who pipped Risca 35-29, are tied at the top on 10 points with Brecon, while Penallta, who beat local rivals Nelson 17-10, are one point behind after two successive victories.
In Division 1 Central, Rhiwbina were forced to come from behind at Rumney before heading home with a 25-18, bonus-point win. The Squirrels trailed 18-8 at the break, but ran in three second half tries.
Scrum half Alex Kerr and right wing Alex Cooke each scored two tries after Roger Mahoney and Callum Macdonald had crossed for the home side to give them a 10 point lead. It didn’t help the Rumney cause that they had a player sent to the sin-bin in the second half and Josh Moscardini added a conversion and penalty for the visitors.
Five teams remain unbeaten after two rounds, with reigning champions Treorchy sitting on top of the table after a thrilling 28-23 away win at Mountain Ash. Ystrad Rhondda also posted another bonus-point win, 31-20, to stay on 10 points with Treorchy and Rhiwbina.
Bala pushed Nat Conwy all the way in their Division 1 North clash, leaving with a losing bonus point in a 22-20 defeat, while reigning champions Pwllheli were happy to leave Caernarfon with a 17-12 victory to remain tied at the top on nine points with Nant Conwy and Llangefni, were won 24-17 at Bethesda.
