Noel Owen, Harri Jones and Jenson Rowlands notched the goals which earned Trearddur Bay the spoils at Eithin Duon.
The game began in a cagey manner, with both teams battling hard.
In the 15th minute, Harri Hughes broke through the defence and set up Noel Owen, who calmly slotted the ball home.
Despite taking the lead, Bay had to remain solid, with 16-year-old keeper Owen Griffiths pulling off a string of impressive saves to keep Llanrug at bay.
Bay’s second goal came via a well-delivered inswinging corner by Casey Gregg. Harri Jones found space and headed in.
The second half saw Llanrug come out strong, but young Owen Griffiths stepped up again, making two massive saves to preserve his second consecutive clean sheet.
While the home side continued to fight, Bay added a third goal on the hour. Rowlands, who later received MOTM from Llanrug, finished with a clever toe-poke after some excellent work by striker Noel Owen.
Luke Allaway’s goal four minutes into stoppage time after the 90 clinched maximum points for jubilant Nefyn.
The Penwaig were two-up after 17 minutes courtesy of captain Elgan Jones and Tristan Harrison, but Cameron Berry pulled one back on 24.
Nefyn were left with problems after Harrison was sent off for a second yellow with 39 on the clock.
Chris Evans levelled for Bay on 55 and the hosts now looked favourites to go on and beat the 10 men, yet it was Nefyn who bagged the decider through Allaway after 94.
Man of the Match Corey Lundstram scored twice for Phoenix in a great win over Prestatyn-based visitors Bow.
Lundstram netted from the penalty spot after 38 and 66 minutes, Billy Sieben and Cody Williams also on the mark.
Barry Roche and Liam Brown replied for Bow, who had keeper Martin King dismissed for two yellow cards on 65.
A very pleasing two-goal win for the Anglesey aces at Cae Stanley on Sunday.
Gaerwen got on the score sheet from a lovely goal by Rhodri Roberts assisted by Oisin Mcareavey on the eight-minute mark.
This was followed by a cracking goal from Christopher Williams a minute later, Mcareavey the provider again.
Bont and Gaerwen both produced some really good football. Both sides created further chances, but it remained 2-0.
Captain Osian Hughes-Jones and sub Iwan Jones were among the scorers at Nantlle picked up all the points at Top Park.
Daniel Cunnah’s 87th minute net-finder sealed a thrilling 5-4 victory for Mochdre after a nine-goal stormer at Bryniau.
Charles Craig and Charlie Dales bagged two apiece for Pentraeth, who had sub Dylan Jones red-carded on 87.
Solomon Moore (2), Riley Cranham, Aidan Roberts and Cunnah hit back to grab the result for Sports.
Caio Jones was a four-goal hero as the Darans rattled up seven at Ffordd Las.
Charlie Jackson and Gethin Wakeham (pen) were the other Llanberis marksmen, Deiniol Bower responding.
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