The Ricoh Arena is the venus for the double-header. First up is the meeting between defending champions the Ospreys and Guinness Premiership high-flyers Gloucester.
Cup form favours the Welsh side. Gloucester, who reside in 2nd place in the Guinness Premiership, have won just one of their last six "domestic" cup semi-finals since 1990: 16-11 over Leicester at Kinsgholm on 29 March 1997.
This season represents the first time that Gloucester have progressed beyond the pools since the EDF Energy Cup first introduced group stages in season 2005/06. Gloucester have won their last four EDF Energy Cup matches since losing 26-29 at Wasps on 4 November 2007. The Cherry & Whites only previous defeat to a Welsh side in this competition was to the Ospreys, 19-49, at Liberty Stadium on 29 September 2006.
Ospreys, who currently lie in 3rd spot in the Magners League table, have won just two of their last five games in all competitions. The reigning EDF Energy Cup holders are bidding to make it to the Twickenham final for the third year running, but their loss at London Irish in the pool phase ended a seven match winning run in this competition.
The two sides have met on four previous occasions with honours even at two wins apiece. Their two prior encounters in the EDF Energy Cup ended 23-7 in favour of Gloucester at Kingsholm on 1 October 2005, and 49-19 to Ospreys in Swansea on 29 September 2006.
The second match of the day is a clash of two sides who have performed will in cup competitions this season. Cardiff Blues qualified as top seeds in the Heineken Cup after winning six games on the spin. While Northampton Saints were also unbeaten in the European challenge Cup Pool phase.
Cardiff are currently in 7th place in the Magners League table, and have won their last four matches in all competitions. The Blues have appeared in one previous semi-final match, where they lost out to the Ospreys, 10-27, at Millennium Stadium in the EDF Energy Cup on 24 March 2007. The Blues have a superb record against English teams, remaining unbeaten in the last ten such encounters since losing 20-42 at Leicester in the EDF Energy Cup on 3 November 2007.
Northampton Saints reside in 8th spot in the Guinness Premiership, and are the only one of the four semi-finalists in the EDF Energy Cup who have played at the Ricoh Arena before; doing so during their 13-30 defeat to Wasps in the semi-final of the Heineken Cup on 22 April 2007. The Saints have won their last four "domestic" cup semi-final matches since the 10-25 reversal to Saracens at Franklin's Gardens at this stage in the 1997/98 event. Northampton have won four of their last five games against Welsh teams.
The two sides have never previously met.
Gloucester Rugby v Ospreys
At Ricoh Arena, Saturday 28 March, 2.30pm (Live on BBC)
Referee: Nigel Owens (WRU).
Touch Judges: Nigel Whitehouse (WRU) & Jonathan Mason (WRU).
TMO: Derek Bevan (WRU).
Gloucester's EDF Energy path to the Semi-Finals
Pool A: London Wasps (H) Won 24-19 (Vainikolo try; Walker try, conv, 3 pens, Lamb drop)
Pool A: Newport Gwent Dragons (H) Won 25-20 (Vainikolo 2, Balshaw, S.Lawson tries; Barkley conv, pen) Pool A: Newcastle Falcons (A) Won 11-10 (Satala try; Barkley 2 pens)
Ospreys' EDF Energy path to the Semi-Finals
Pool C: Harlequins (H) Won 24-23 (S.Williams, Bowe tries; Hook conv, 4 pens)
Pool C: Worcester Warriors (H) Won 37-22 (Walker, Bowe, Henson, S.Williams tries; Hook conv, 5 pens) Pool C: London Irish (A) Lost 19-23 (Walker try; Hook conv, 4 pens)
Cardiff Blues v Northampton Saints
At Ricoh Arena, Saturday 28 March, 5.15pm (Live on BBC)
Referee: George Clancy (IRFU).
Touch Judges: Alan Biggs (RFU) & Ashley Rowden (RFU).
TMO: David Matthews (RFU).
Blues' EDF Energy path to the Semi-Finals
Pool B: Sale Sharks (A) Won 18-17 (Halfpenny , Mustoe tries; Blair conv, pen; Sweeney pen) Pool B: Leicester Tigers (H) Won 23-9 (J.Robinson, Spice tries; Blair 2 conv, 3 pens) Pool B: Bath Rugby (H) Won 24-18 (Filise, Molitika tries; Blair conv, 4 pens)
Saints' EDF Energy path to the Semi-Finals
Pool D: Bristol Rugby (H) Won 30-17 (Diggin, Ashton, Mayor, Dickson tries; Everitt 2 conv, 2 pens) Pool D: Saracens (A) Lost 19-33 (Foden, Wilson tries; Myler 3 pens) Pool D: Scarlets (H) Won 33-20 (Ashton 2, Reihana, Lamont tries; Myler 2 conv, 3 pens)