With less than twenty minutes remaining it was looking like being a frustrating afternoon for Glantraeth as constant pressure to the home goal had failed to make a breakthrough only for substitute Osian Pritchard to slam in what proved the winner in the 72nd minute, reacting quickly when Penrhyn keeper Richard Morgan made a mess of punching clear a Jonathan Peris Jones corner kick from the left.
It was no more than Glan deserved as they had bossed the second half with great football while Penrhyncoch seemed more intent on disputing every decision made by referee Martin Williams. As against Holyhead two weeks back Glan rose above all this and concentrated on the job in hand although it could be said they made hard work of it before finally ending up worthy winners.
The game had started tamely with Glan playing up the Cae Baker slope and there were 25 minutes gone before either goal was really threatened as Glanís Paul Rowlands blasted in a shot that was deflected for a corner.
Although the visitors were playing the better football there was little to choose between the sides at this stage but on 35 minutes Penrhyn came closest to taking the lead as their best player Dylan James sent in a dipping free kick that was only inches too high. David Alan Jones missed a great opportunity to put Glan ahead six minutes later as he rose to meet a ball in from Peris Jones only to head wide of the goal.
Jones was again the threat four minutes into the second period heading over another Peris Jones cross. Gareth Wyn Roberts cleverly made space for a cross that was cleared as Glan began to really turn the screw on their opponents.
As in so many games of late the Anglesey side were enjoying long spells of possession but finding it difficult to turn that possession into goals and there was a warning at the other end on 55 minutes as Llyn Hughes headed wide from a good position.
A header from Peris Jones was saved by Morgan then a Richard Owen effort from fully forty yards down the slope skidded just wide as Glan continued on top.
With the game so delicately balanced Glan could afford no mistakes at the back and Llion Davies did well on 67 minutes to get something on the ball and deflect a shot from Chris Williams for a corner as the Penrhyn striker closed in on goal.
Four minutes later a Richard Owen free kick almost caught everyone out as it just drifted wide of a post with a home player getting the last touch and from the resulting corner kick Osian Pritchard got the vital goal.
Penrhyn were not finished with Joe Sherwood volleying over on 82 minutes but Glan should have added a second in the closing minutes as a good run from Chris Saxon gave Peris Jones an opening but his shot was directed straight at the keeper then Saxon himself had a the kind of chance in front of goal that he usually gobbles up but his header from an Owen free kick went harmlessly over.
Glantraeth: Gareth OJ Roberts, Jonathan Peris Jones, Darren Jones, Emyr Rowlands, Sion Parry, Richard Owen, Paul Rowlands (Paul Whelan 83), Chris Saxon, Gerallt Jones (Llion Davies 56), Gareth Wyn Roberts, David Alan Jones (Osian Pritchard 56).