The winners of Sunday's intriguing all-Irish clash between top seeds, Munster Rugby, and Ulster Rugby will play their semi-final at the 50,000-capacity Aviva Stadium on Saturday, 28 April against the winners of the competition's opening quarter-final between Edinburgh Rugby and four-time champions, Toulouse.
If English champions, Saracens, come through Sunday's much anticipated contest with ASM Clermont Auvergne, they will meet the winners of the Leinster Rugby v Cardiff Blues game in the semi-final at Twickenham Stadium on Sunday, 29 April. However, if Clermont defeat Saracens, they will take on either Leinster or Cardiff Blues at Stade Chaban-Delmas.
The Aviva Stadium hosted last season's Heineken Cup semi-final between Leinster and Toulouse, while two tournament semi-finals have been played at Stade Chaban-Delmas - Toulouse v Munster in 2000 and Toulouse v Biarritz Olympique in 2004. Twickenham Stadium, which will stage this season's Heineken Cup final on 19 May, has hosted one semi-final to date when London Irish met Toulouse in 2008.
Following the Amlin Challenge Cup semi-final draw at the conclusion of the Pool stage, the much anticipated clashes this weekend of Toulon and Harlequins, and of London Wasps and Biarritz, will have the added incentive of offering the winners a home semi-final and taking them one step closer to the tournament final at the Twickenham Stoop on Friday, 18 May, the eve of the Heineken Cup showpiece occasion.
Toulon or Harlequins will play the winners of the Stade Francais Paris-Exeter Chiefs game on Friday, 27 April, and if Biarritz Olympique defeat London Wasps, they will meet the winners of Brive v Scarlets on Saturday, 28 April. However, if London Wasps are victorious, they will play either Brive or Scarlets on Sunday, 29 April.
HEINEKEN CUP SEMI-FINALS
Saturday, 28 April
Munster Rugby or Ulster Rugby v Edinburgh Rugby or Toulouse - Aviva Stadium, Dublin (capacity: 50,000)
Sunday, 29 April
Saracens or ASM Clermont Auvergne v Leinster Rugby or Cardiff Blues - Twickenham Stadium (capacity: 82,000) or Stade Chaban Delmas, Bordeaux (capacity: 34,000)
Heineken Cup final- Twickenham Stadium, Saturday 19 May (5.00pm)
AMLIN CHALLENGE CUP SEMI-FINALS
Friday, 27 April
Toulon or Harlequins v Stade Francais Paris or Exeter Chiefs
Saturday, 28 April / Sunday, 29 April
London Wasps or Biarritz Olympique v Brive or Scarlets
Amlin Challenge Cup final - Twickenham Stoop, Friday 18 May (8.00pm)
• The kick-off times for the Heineken Cup and the Amlin Challenge Cup semi-finals will be announced following this weekend's matches
• Tickets for the games will go on sale through the participating clubs this weekend with additional tickets expected to be available for public sale. For details, see ercrugby.com