Dublin - Irish provinces Leinster and Munster both enjoyed home wins in the quarter-finals of the European Champions Cup on Saturday.
Three-times European kings Leinster saw off England's Wasps 32-17 in Saturday's opening last-eight clash at Dublin's Lansdowne Road.
Munster, who've won two European titles, then overcame four-times champions Toulouse with a 41-16 defeat of the French giants at Limerick's Thomond Park.
Leinster will have an away semi-final against the winners of Sunday's all-French clash between Clermont and Toulon.
Sunday's other quarter-final sees reigning champions Saracens, also the English title-holders, welcome Glasgow to north London.
If Saracens win, they will travel to Ireland for a Lansdowne Road clash with Munster. But if Glasgow are triumphant, Munster must head to Edinburgh's Murrayfield for a semi-final on Scottish soil.
Wasps's South Africa back Willie Le Roux made an extraordinary error as two-time European champions Wasps, the Premiership leaders, to deprive his side of an important early try.
After fine work by Australia's Kurtley Beale, Le Roux was sent clear with the line at his mercy.
But with no Leinster defender near him, the Springbok opted for a needless dive over the line only to lose control of the ball, with his score disallowed.
It proved a costly error for Wasps who saw Irish province Leinster, table-toppers in the Celtic League, score three first-half tries through Isa Nacewa, Jack Conan and Robbie Henshaw.
But two Wasps tries in seven second-half minutes from the speedy Christian Wade and Jimmy Gopperth brought the visitors back into contention as the game reached the hour mark.
However, Leinster regrouped and Fergus McFadden's try five minutes from time sealed victory n a match where Ireland fly-half Jonathan Sexton kicked 12 points.
Wasps coach Dai Young tried to downplay Le Roux's error by insisting it was early enough in the game not to have been the decisive moment of the match.
"Willie, obviously, it's going to be well documented... If he had put that ball down, we could have been 10-8 up. We would have been pretty pleased with that, because we were under pressure," Young said.
"I think it may have calmed us down a little bit, but I know a lot of people will point to that as a turning factor," the former Wales and British and Irish Lions prop added.
"It certainly didn't help us, but I'm not saying it was a turning factor because we had 55 minutes to play. We had plenty of time to turn that around."
Leinster started with an inexperienced backline, while Wasps fielded an international class back three of Beale, Christian Wade and Le Roux.
But that did not stop Leinster racing into an early lead, with 21-year-old fullback Joey Carbery central to everything they did well in what had been billed as an 'audition' for the upcoming Lions tour of New Zealand.
"Joey is very, very brave," said Leo Cullen, the Leinster head coach. "He's not afraid to try things."
Munster, who in October were left mourning Anthony Foley after their coach died suddenly on the eve of a Champions Cup pool match in Paris, outscored Toulouse by four tries to one as they reached a first semi-final in Europe's elite club competition in three years.
But Munster were just 13-9 in front at half-time, thanks to John Ryan's early try. Ireland's CJ Stander crossed in the second half before Paul Perez's breakaway try cut Munster's lead to 24-16.
Munster, however, put the result beyond doubt with two late tries from Darren Sweetnam and Andrew Conway as Toulouse chased the game.