Tredegar Ironsides were the team of the day in the Swalec Plate, claiming a terrific 31-8 win away at Rhymney, despite sitting a league below in Division Four East.
Jonathan Mills scored two of the away sides four tries and Ryan Hall claimed 11 points from the boot to seal a memorable win.
Risca of Division Four East put in a terrific performance to stun Croesyceiliog of Division Three East 20-15 away from home, while the students of Cardiff University pulled off another upset, beating Fairwater 17-14.
Rhydyfelin were the big scorers of the day, running home six tries on their way to a 41-0 demolition of Cilfyndd.
Mike Huckeridge claimed a try as Treherbert of Division Two East overcame a late scare to edge out Brecon 14-12, and
Tonyrefail came out in top of the all-Division Four East clash, beating Pentyrch 27-17 in a thrilling contest.
Elsewhere Mountain Ash beat Nelson 26-6, and Blaina claimed an impressive away win as they beat Division Three East rivals Abertillery Blaenau Gwent 20-8.
Abercarn pulled off the shock of the round in the Swalec Bowl, the Division Five East side beat Abergavenny of Division Two East 21-17.
Tries from Nicky Lloyd and Matthew Johnson had put Abercarn 13-12 ahead at half-time before Jack Davies put the home side 20-12 ahead. A late try from Abergavenny set up a tense finish, but the home side bravely held on to ensure a famous win.
John Mayler scored two tries as Old Penarthians gained an impressive 20-0 victory away at Canton and Ross Howells also claimed a brace as Ferndale beat Rhigos 20-8, Luke Rees claimed the other try for the Bulldogs.
Dowlais were the big scorers of the day as they ran in six tries to beat St Albans 45-3.
Crumlin put in a great performance away from home to beat Cefn Coed 34-0, while Usk also won away from home, they beat Llanhilleth 10-17.
Rhiwbina won 19-14 away at Cardiff HSOB, and Pontyclun also claimed a narrow win, beating Bridgend Sports 15-9. In the remaining game in the Swalec Bowl, Abervan failed to field a side against Newtown.
Wales U20 captain Tom Phillips and performance psychologist Dr Rich Neil explain why spending three days at Monmouth RFC has further strengthened the togetherness of the squad ahead of the #WorldRugbyU20s
Alongside Scarlets flanker James Davies and Cardiff Blues centre Cory Allen, three Wales Sevens core players have made the extended training squad for GB Sevens. Wales Head coach Gareth Williams tells WRU TV's Graeme Gillespie why Luke Treharne, Sam Cross and Luke Morgan earned selection in the initial training squad for Rio.
Wales Sevens head coach Gareth Williams tells WRU TV's Graeme Gillespie he has had to overcome a number of injuries before naming a competitive squad for this weekend's penultimate round of the World Series in Paris.
Merthyr were officially crowned champions of the SSE SWALEC Championship at Dowlais on Saturday where captain Andy Powell paid tribute to his side who have earned promotion to the Principality Premiership
Coleg y Cymoedd's season has had a spectacular ending with victory in two cup finals and a massive victory over one of the best rugby playing schools in the world - Welsh coach Warren Gatland's old alma mater, Hamilton Boys' High School.
WRU chief executive Martyn Phillips hosted the second meeting of the WRU Youth Board last weekend ahead of the Judgement Day IV regional double-header. Tthe board, made up of 15 under-21-year-olds from around Wales, heard presentations from head of participation Ryan Jones, policy and integrity manager Jeremy Rogers and national women's rugby manager Caroline Spanton, with Pro Rugby Wales CEO Mark Davies also on hand to hear the range of views aired.
Wales duo Rhun Williams and Liam Belcher, who makes a welcome return after five months of injury woe, look ahead to next month's World Rugby U20 Championship in Manchester where they will face Ireland, Georgia and New Zealand.