La Rochelle will host Leinster in their Champions Cup semi-final on Sunday, May 2, at the Stade Marcel Deflandre.
Their head coach Ronan O'Gara will be hoping to orchestrate the Blues' semi-final downfall en route to his club's first Champions Cup success as he did during his playing days with Munster in 2006.
Four-time champions Leinster booked their place in the last four on Saturday with an impressive come-from-behind quarter-final win at reigning champions Exeter Chiefs and they also inflicted some semi-final pain on O'Gara and Munster in 2009 on their path to a first European title.
La Rochelle, who hammered Sale Sharks by 24 points in the quarters, will retain home advantage for the semi-final which will kick-off at 3pm (Irish time).
The other semi-final is a mirror image, four-time winners Toulouse against first-time semi-finalists Bordeaux-Begles, who knocked out last season’s runners-up Racing 92.
Toulouse, who beat Clermont Auvergne last time out, will host the tie at the Stade Ernest Wallon with kick-off at 3pm on Saturday, May 1.
Both games will be broadcast on BT Sport, with Toulouse v Bordeaux also carried free-to-air on Virgin Media and Channel 4.
Ulster's Challenge Cup semi-final away to Leicester Tigers will take place on Friday, April 30. Kick-off at Mattioli Woods Welford Road will be at 8pm.
Bath welcome Montpellier to the Recreation Ground at 8pm the following day. Again, both semi-finals will be live on BT Sport.
Toulouse v Bordeaux-Bègles, Stade Ernest Wallon (3pm)
La Rochelle v Leinster Rugby, Stade Marcel Deflandre (3pm)
Saturday, May 22
Leicester Tigers v Ulster Rugby, Mattioli Woods Welford Road (8pm)
Bath Rugby v Montpellier, Recreation Ground (8pm)
Friday, May 21