Substitute Steve Blenkinsop turned the game as Guilsfield closed the gap on second place in the JD Cymru North with s superb fightback.
Trailing 2-0 at home to Llandudno, the striker was introduced midway through the second half and contributed two goals to level the game before Adam Jenkins scrambled home a late winner.
Llanfair United have launched their survival fight following a brilliant 3-1 win at Llangefni Town, their first victory of the season.
Newtown have booked their place in the quarter-finals of the JD Welsh Cup following an accomplished 4-1 victory over Rhyl.
The Robins were pegged back 1-1 in the first half, but took control of the tie to move into the last eight.
No change in the MMP Mid Wales League where league leaders Llanidloes Town won 5-2 at Kerry, and chasers Builth Wells, Bow Street, Welshpool and Caersws all won.
Waterloo Rovers maintained their pressure on the top three of division two while Churchstoke pulled off a big win at Knighton.
Holders Guilsfield Reserves are through in the Llansantffraid Village Cup following their 5-2 win at Trefonen.
JD Welsh Cup, fourth round
Newtown 4, Rhyl 1
JD Cymru North
Guilsfield 3, Llandudno 2
Llangefni Town 1, Llanfair United 3
MMP Mid Wales League
Division One
Bow Street 4, Montgomery Town 0
Builth Wells 3, Llansantffraid Village 1
Caersws 7, Tywyn Bryncrug 0
Carno 0, Radnor Valley 0
Four Crosses 0, Berriew 4
Kerry 2, Llanidloes Town 5
Welshpool 5, Aberaeron 2
Division Two
Aber Uni 4, Abermule 1
Borth Utd 1, Waterloo Rovers 3
Dolgellau 3, Penparcau 1
Dyffryn Banw 0, Newbridge-on-Wye 2
Forden Utd 3, Rhayader 3
Knighton Town 1, Churchstoke 4
Presteigne 1, Machynlleth 5
JT Hughes Montgomeryshire League
Division One
Bishops Castle 7, Llanfair United Reserves 0
Llangedwyn P, Llanrhaeadr Reserves P
Maesyrhandir 3, Llanfyllin Town 1
Trewern 3, Meifod 0
Division Two
Churchstoke Reserves P, Four Crosses Reserves P
Llanfyllin Town Reserves v Kerry Reserves
Llanfechain v Welshpool Town Reserves
Newtown Wanderers P, Caersws Reserves P
Boys and Boden Montgomeryshire League Cup, second round
Waterloo Rovers Reserves 0, Llanymynech 3
Llansantffraid Village Cup, second round
Trefonen 2, Guilsfield Reserves 5