The Blues last played in the Millennium Stadium in May 2009 in a thrilling 26-26 draw with Leicester Tigers in the Heineken Cup semi final. The match, which was watched by a record 44,000 fans, went into extra time before a penalty shoot out saw the Blues eliminated from the competition.
The Blues now face an Ospreys side who are challenging for a top four place and whose sole defeat in their last nine RaboDirect PRO12 matches since November was 10-22 to Connacht in Galway in round 15.
Ospreys only two previous visits to the Millennium Stadium were both semi-final encounters in the Anglo-Welsh Cup, in 2007 and 2008, winning them both, against Cardiff Blues and Saracens respectively.
It will be a challenge for the Blues who will be looking to regain some form having slipped to three straight defeats in the RaboDirect PRO12 since their 17-16 victory against Edinburgh at Murrayfield in February. And have not beaten Ospreys since a 27-25 victory at the City Stadium on New Year's Eve 2010.
Speaking ahead of the match, Cardiff Blues Director of Rugby Phil Davies said,
"We've got plenty to play for and playing at the Millennium Stadium just gives it that extra edge.
"Coming off the back of Wales winning the Six Nations championship is great and hopefully it's an occasion that can showcase the regional game in Wales.
"Facing the Ospreys is a challenge and we've certainly not performed to the standards we have aspired to, we have performed well, but we are coming up against arguably the best pack in the competition.
"It's not going to be easy but it's a challenge we are looking forward to and we will be making it a challenge for the Ospreys as well.
"We have to work well as a collective unit. There will be some outstanding players on display and there will be some intriguing battles all over the pitch.
"A lot of players know each other well but at the end of the day it's about Cardiff Blues v Ospreys."
All four regional coaches have agreed that the roof will be closed which is sure to add to the atmosphere at the iconic venue. Hopefully this special occasion will be an opportunity to entertain rugby lovers from all corners of the regions.
Cardiff Blues season ticket holders are reminded that their tickets for Judgement Day need to be collected from the Cardiff Arms Park Ticket Office before kick off on Saturday. Please note that the Ticket Office closes at 4pm on Friday 29th March.
Season ticket holders wishing to renew their season ticket on the day of the double header can do so in the Martyn Williams Pack Bar situated behind the Family Stand.
The Gareth Edwards Lounge upstairs in the clubhouse will be open to the general public from 12 midday on Saturday, with the downstairs Members Bar also opening at 12. It's the ideal venue to meet ahead of the matches.
Following the final whistle of the Cardiff Blues v Ospreys match the ever popular 4th Street Traffic will be performing in the Arms Park Courtyard at 7.00pm.
Cardiff Blues 15 Leigh Halfpenny 14 Owen Williams 13 Gavin Evans (c) 12 Dafydd Hewitt 11 Harry Robinson 10 Rhys Patchell 9 Lloyd Williams
1 Sam Hobbs 2 Marc Breeze 3 Scott Andrews 4 Filo Paulo 5 Lou Reed 6 Michael Paterson 7 Sam Warburton 8 Luke Hamilton
16 Kristian Dacey 17 Thomas Davies 18 Taufa'ao Filise 19 Robin Copeland 20 Rory Watts-Jones 21 Lewis Jones 22 Ceri Sweeney 23 Gareth Davies