Tommy Rowlands struck twice in the second half to earn Builth Wells the points at Clywedog Park.
Josh Astley gave Albion a ninth-minute lead with his 18th goal of the season, Tom Smith giving the assist.
It was 1-0 at half time, but three minutes after the restart Thomas Offa equalised.
Alex Williams restored the home advantage on 59 minutes, but Rowlands struck after 68 and 81 to secure an away win.
Goals galore at The Rock, where Gresford’s Rob Reynolds led the charge with a quartet of strikes.
Callum Wakefield (2), Connor Groom, Martyn Elms and Elis Rowland bagged the rest for the hosts, Will Owen-Ford (2), Mabon Owen (2) and Aaron Jones sharing the Port replies.
Just the one goal separated the teams at Trefdraeth.
Home side Glantraeth progressed to the North Wales Coast West Premier Division Cup final with a victory over Llanrug secured by a Gethin Davies net-finder midway through the second half.
Glan will now meet Llanberis in Wednesday’s final at Llanfairpwll (6.30 pm).
Extra time goals from Cameron Buckley and Luke Jones earned Trearddur Bay their place in Wednesday’s final against Penmaenmawr at Bontnewydd (6.30 pm).
Earlier, captain Lennon Owen, Casey Gregg and Noel Owen had found the net for the Anglesey side, but replies from Connor Morris (2) and Tate Walker necessitated another half-hour of play.
Kinmel trailed 2-0 and 3-2 but never stopped fighting and Trearddur needed to pull out all the stops to edge the tie in extra time.
Jonny Cyster opened the scoring for Llanberis on 12 minutes, but Morgan Roberts levelled soon after and it stayed 1-1 till half time.
The winner arrived in the 58th minute from a familiar source – noted Phoenix goal-getter Benn Lundstram.
The Darans had Deio Roberts red-carded in the 90th minute.
Report carried by Grassroots North Wales on Saturday.
Match report published by Grassroots North Wales on Sunday
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