Penydarren BGC, from the fifth level of Welsh football, are gatecrashing the Welsh Premier League party.
The boys from Merthyr Tydfil, who play in the South Wales Alliance, are the only team from outside the Welsh Premier League to qualify for the JD Welsh Cup quarter-finals.
Pen defeated Pontypridd Town 2-1, thanks to two goals from Chris Owens, and join Llandudno, The New Saints, Carmarthen Town, Aberystwyth Town, Connah’s Quay Nomads, Newtown and Bangor City in the fifth round.
Llandudno were given a scare by Cymru Alliance club Ruthin Town and needed extra time before going through 4-3.
Toby Jones scored the only goal before half-time to give the home team a lead, while goals from Tom Roberts (60 mins) and Ilan Hughes (67) gave Ruthin a 2-1 lead.
Assistant manager Matty Williams equalised on his debut and is the 20th different scorer for Llandudno since they were promotion to the Welsh Premier in 2015.
That came after 87 minutes and Llandudno almost snatched the winner in the closing seconds when Marc Williams ran clear, but dragged his shot wide with only goalkeeper Ryan Goldston to beat.
The same player made amends two minutes into extra time when he dinked the ball over Goldston and then Toby Jones made it 4-2 when cut inside a defender before shooting home.
Ruthin kept battling and pulled a goal back when Osian Davies scored, but Llandudno held on to win at the giant hospitality stadium.
Llandudno FC: David Roberts, Daniel Taylor,James Joyce, Daniel Shaw, Michael Williams, Samuel Hart, Matthew Williams, Daniel Hughes, Toby Jones, Marc Williams, Marc Evans. Patrik Rutter, Lee Thomas, Iwan Williams, Harri Jones.
Ruthin Town: Ryan Goldston, Craig Wilkinson, Tomos Roberts, Michael Sharples, Kevin Evans, Ilan Hughes (capt), Jordan McCarter, Osian Davies, Llyr Morris, Gwion Owen, Garmon Hafal. Subs: Will Owen, David Finnie, Will Roberts, Matthew Williams, Dylan Jones (gk).
Bangor City fought back from behind to beat Llanrhaedr-ym-Mochnant 3-2.
Iwan Matthews scored from a penalty for Llanrhaedr after eight minutes, while new Bangor signing Yves Zama equalised on his debut five minutes later.
Joel Bembo-Leta, another new Bangor signing making his debut, gave his team a 2-1 lead midway through the half and the same player scored his teams third goal.
Bangor looked comfortable at 3-1 ahead, but they had Laurence Wilson sent off for a second bookable offence.
Matthew then netted his second for Llanrhaedr, but they had Dan Kelly dismissed for a second booking and Bangor held on for victory.
Newtown needed extra time and penalties to overcome Flint Town United and book their place in the last eight.
Alex Fletcher put the Robins ahead early, while Luke Boundford’s own goal gave Flint their equaliser.
Newton regained the lead in extra time when Ryan Kershaw netted and Richie Foulkes equalised to make it 2-2 after extra time.
Goalkeeper Dave Jones saved two spot kicks for Newtown and Jamie Reed hit the spot-kick winner to send them through 4-3.
Connah’s Quay Nomads and Carmarthen Town both overcame Huws Gray Alliance opposition to earn their place in Monday’s draw.
Joe Chaplin fired Porthmadog ahead after eight minutes at Nomads, while Michael Bakare equalised two minutes later from a free-kick.
Michael Wilde fired Nomads in front after 34 minutes and George Horan completed the 3-1 scoreline (85 mins).
Carmarthen defeated Airbus 4-1 at the Hollingsworth Group Stadium thanks to goals from Liam Thomas (2), Aiden O’Kelly and Liam Walsh.
Luke Busumbro was on target for Airbus.
In the only all-Welsh Premier League match of the round Aberystwyth Town won 1-0 at Cardiff Met with Malcolm Melvin’s header on 37 minutes proving to be the winner.
The JD Welsh Cup quarter-finals draw will take place during Monday night’s Heno on S4C (7pm).
JD Welsh Cup fourth round results: Caernarfon Town 1, The New Saints 3; Pontypridd Town 1, Penydarren Boys and Girls Club FC 2; Airbus Broughton 1, Carmarthen Town 4; Cardiff Metropolitan 0, Aberystwyth Town 1; Connah’s Quay Nomads 3, Porthmadog 1; Flint Town United 2, Newtown 2 (Newtown won 4-3 on penalties after extra time); Llanrhaeadr Ym Mochnant 2, Bangor City 3; Llandudno 4, Ruthin Town 3 (after extra time).