After Cardiff's victory over Newport by 20-14 on Friday evening, the other three quarter-finals on Saturday saw victories for Llanelli and Pontypridd in the afternoon and Ebbw Vale in the night match.
Wales scrum half Robert Howley had scored the try that took Cardiff to a 20-14 win over holders Newport at the Arms Park and it was Cup kings Llanelli who overcame Bridgend to win by 46-24.
Bridgend struck early with tries by Adrian Durston and Aisea Havili, but Llanelli stormed away in the second half as Ian Boobyer touched down two of their five tries and outside half Stephen Jones kicked 21 points, while former Scarlet, Craig Warlow, notched 14 for Bridgend.
Pontypridd full back Brett Davey kicked five first-half penalties that in the end proved the difference against a game Caerphilly side. Pontypridd won
46-31 with centre Sonny Parker and the Caerphilly forward Andrew Williams both grabbing braces of tries.
A magnificent effort by Pontypool saw them almost add Ebbw Vale to their scalps after having already knocked out Swansea. The Vale won 27-22 thanks to a late try by centre Paul Matthews. Kickers Gareth Cull and Byron Hayward had fought a good duel and Pontypool Park was aflow with a splendid crowd for the evening match.
The draw brought out Pontypridd first and then their opponents, Cardiff, while Llanelli were drawn against Ebbw Vale or Pontypool, but a few hours after the draw it was Ebbw Vale who won through.
DRAW for PRINCIPALITY CUP SEMI-FINALS:
(both to be played at the Millennium Stadium, Cardiff)
LLANELLI vs EBBW VALE 3pm
PONTYPRIDD vs CARDIFF 5.30pm
Pontypridd and Cardiff have met three times in the Cup - Pontypridd won 9-7 home in 1978/79 and 13-6 away in 1979/80, while Cardiff won 8-6 in the 1993/94 semi-final.
Llanelli have beaten Ebbw Vale in all their five previous meetings - 10-4 in the 1975/76 semi-final; 15-9 home in 1979/80; 41-0 home in 1987/88; 19-12 in the 1997/98 final at Bristol and by 38-26 in a 1999/2000 semi-final.
Sam Cross and Luke Treharne have been named as co-captains of the Wales Sevens side as head coach Gareth Williams names his 12-man squad to play in the first leg of the HSBC World Series in Dubai next weekend.
Bedwas head coach Steve Law and players Nicky Griffiths and Alun Rees extol the virtues of the close knit club as they prepare to host third place RGC 1404 - who are one place head of them on the Principality Premiership points table - on Saturday.
Many of the Wales squad have said Diolch (thank you) to someone who played an important part in their early playing days by nominating them to be invited to the Wales v South Africa match. One person, Gowerton Comprehensive geography teacher Mr Dean Mason was nominated by two of his former pupils, Dan Biggar and Sam Davies.
The second WRU disability rugby pilot has been delivered, this time in Caerphilly schools, culminating in a festival at the Caerphilly Centre of Sporting Excellence, Ystrad Mynach tomorrow. Plans are in place to set up a Disability Rugby Club in Newbridge to provide long-term playing opportunities.
WRU TV: Hear from inside the Wales camp as Neil Jenkins discusses this weekend's clash with South Africa and how the squad are looking to put in a strong performance to round of the 2016 Under Armour Series