Pontypridd recorded a magnificent victory at Vicarage Road as they became the first Welsh side to reach the semi-finals of the PARKER PEN SHIELD.
A try in each half for the Welshmen put paid to the English premiership side and made them only the sixth team in 24 quarter-finals to win away from home.
While there was plenty of attacking intent from the visitors in the first half, they had to rely on the woodwork at the death to deny the Saracens as former Springbok outside-half Jannie De Beer struck an upright with a 45-metre penalty that would have won the game.
More than that, Ponty then had to suffer a scrum under their own posts after a knock-on when the ball rebounded back from the penalty.
Saracens went for the drop goal, but Ponty somehow managed to force De Beer, the man who once drop-kicked England out of the Rugby World Cup finals in Paris with five drop goals, onto his left foot.
De Beer's kick drifted wide and the game ended as soon as the ball went dead.
Ponty were good value for their victory as they scored a try in each half to make it a notable day for Welsh rugby with Llanelli also beating Bath in the Heineken Cup.
No 8 Michael Owen was credited with the first try a minute before half-time that gave the visitors a 10-6 interval lead once Brett Davey had added the conversion.
De Beer struck three successive penalties in the first 10 minutes of the second half to hoist Saracens into a 15-10 lead, but Gareth Wyatt skipped away for the vital score five minutes later and Davey once again added a conversion.
After that, it was all about brave and organised defence and Ponty came up trumps - with a little bit of help from the upright.
SCORERS: Saracens: Pens: J de Beer 5. Pontypridd: Tries: M Owen, G Wyatt; Cons: B Davey 2; Pen: B Davey .
Saracens: T Horan; G Arasa, T Shanklin, K Sorrell (A Winnan 47), D O'Mahoney; J de Beer, K Bracken (captain, N Walshe 55); D Flatman (M Cairns 70), R Russell, P Du Randt, S Hooper (K Roche 47), S Murray, K Chesney, T Roques, R Hill.
Pontypridd: B Davey; G Wyatt, S Parker, J Bryant, N Simpason; C Sweeney, P John (captain); G Jenkins, M Davies, D Bell, B Cockbain (G Remnant 50), R Sidoli, N Kelly (D McIntosh 46), R Parks, M Owen.
The WRU has launched a campaign to create a long term legacy for Welsh club rugby by highlighting the advantages of volunteering. Rhian Edwards, a volunteer at Seven Sisters, has enjoyed many benefits of her volunteering at a grassroots rugby club including being part of the Rugby World Cup volunteer workforce after being nominated by the WRU - and the WRU is asking for more people to develop their 'Welsh rugby roots'.
Wales head coach Warren Gatland and captain Sam Warburton say their first prioirty on Sunday in the opening game of the World Cup is to win against Uruguay and not get overly concerned with points difference.
With only days to go until the biggest rugby competition in the world begins, rugby fans visiting Cardiff this autumn will be able to enjoy a special display at National Museum Cardiff as part of the celebrations surrounding the Rugby World Cup.
Geraint John has taken up the new role of WRU elite coach development manager having arrived in Wales last week. WRU TV caught up with him at the WRU rugby department's strategy day at the Millennium Stadium.
The entire Welsh Rugby Union Rugby Department gathered at the Millennium Stadium earlier this week where WRU Head of Rugby Josh Lewsey looked back on a year where structural and strategic changes have seen significant progress made
The Welsh Rugby Union has released a specially produced video to spearhead a new campaign to help promote the values of rugby union. The video, entitled Let us Play underpins the WRU rugby department's philosophy - to engage, transfer and retain players, coaches and referees.