Matthew Morgan put the All Whites on the score sheet, nailing five penalties from outside-half but it wasn't enough to stop Aberavon.
League leaders Pontypridd were held to a 16-16 draw by struggling Cardiff in a messy game at Sardis Road.
Winger Jimmy Norris raced through to score for Cardiff while centre Adam Thomas stormed over the line for the hosts.
"That was a massive improvement," said Cardiff backs coach Lee Jarvis who starred for both Cardiff and Ponty as a player.
"We worked on a few things in the week as far as our attack and defence goes and it's good to see those things come through. But rugby is a simple game and we turned up with an attitude that I haven't seen all season and it showed in the way we played.
"It was nip and tuck right the way until the end. We had our chances in the second half and we let them off the hook a couple of times as well."
Llanelli dominated their mid-table match with Bedwas, winning 28-3 and taking a bonus point in the process.
Wings Jonny Lewis and Lee Williams, centre Nick Reynolds and prop Rhodri Jones scored the home side's tries.
Tonmawr were the victors in a try-fest at Pandy Park, beating Cross Keys 33-28.
The Keys shipped four tries, with flanker Craig Price, lock Jonathan Griffith and wings Gareth John and Kiba Richards going over.
Lock Tom Lampard got the only try for the home side, but Steffan James had an outstanding game at outside-half, landing 23 points with the boot and snatching a losing bonus point in the last minute.
Glamorgan Wanderers recorded their first win of the season, beating fellow strugglers Carmarthen Quins 24-10 the Memorial Ground. Wings Rory Badina and Robin Lock both touched down for the Wanderers.
Pontypool and Llandovery were left in deadlock as they drew, 26-26. There were two tries apiece, with Pooler's coming from wing Oliver Halford and fly-half Shaun Connor, and the Drovers by full-back Lee Rhys and wing Adam Warren.