Risca booked their place in the semi-finals of the SWALEC Plate after ending Cardiff University's cup dream with a thrilling 48-28 victory.
Risca are now the lowest-ranked side left in the competition, but will surely fancy their chances after a stunning eight try haul.
Tries from Rhys Putter and Rhys Carpenter and David Jefferson helped the home side on their way to a 26-14 half-time lead, but it was in the second period that Risca really turned on the style.
Two tries from number 8 Richard Evans and a try each from Nicky Davies, Owen Cooper and Tim Barnes completed the rout, although the students of Cardiff went down fighting and can be proud of their displays in this season's competition.
Tredegar Ironsides pulled off the shock of the day with a 15-0 win over Nantyffyllon. The Division Four East outfit grabbed a try in each half through wing Lewis Pritheroe and centre Craig Monaghan.
Rhydefelin survived a second-half comeback from fellow Division Two East side Mountain Ash to win 21-15 at Parc Duffryn Pennar.
The away side had lead 15-5 at half-time thanks to two tries from Aled Jones, before tries from centre Adrian Owen and Dale Keppin hauled Mountain Ash back into the game.
Two penalties from Geraint Watts kept the home side at bay to ensure Rhydyfelin's passage into the final four.
In the remaining quarter-final game Ammanford ran in three tries as they beat Newcastle Emlyn 28-15.
GB7s women left their England base to train in Wales this week. Olympic Games hopeful Rachael Burford gives WRU TV's Graeme Gillespie her thoughts on Welsh teammate Jasmine Joyce - a 'one touch wonder'
The GB7s women's squad is currently training at Wales' Centre of Excellence where assistant coach Richie Pugh tells WRU TV's Graeme Gillespie some 'tough calls' will have to be made when it comes to finalising the 12 spots for Rio's Olympic Games.
Wales U20's Billy McBryde is looking forward to starting his first game against New Zealand this afternoon in the World Rugby U20 Championship where his side are looking to gain revenge from last week's pool defeat to the Kiwis.