Munster moved five points clear at the top of the Pro12 table with a 29-17 derby win over Leinster, while Glasgow Warriors beat Edinburgh in the first leg of the 1872 Cup on Boxing Day.
Second-placed Leinster were without a host of key men - such as Jamie Heaslip and Sean O'Brien - and they were second best at Thomond Park.
Munster led 14-10 at half-time courtesy of converted tries from Simon Zebo and Ronan O'Mahony after Zane Kirchner's early score had put Leinster in front.
Further tries from Tommy O'Donnell and CJ Stander strengthened the leaders' grip on the contest, with Tyler Bleyendaal scoring nine points from the tee to ensure there was no way back for Leinster by the time Richardt Strauss went over later on.
Glasgow maintained the momentum gained from their famous back-to-back European Champions Cup triumphs over Racing 92 by seeing off Edinburgh 25-12.
The Warriors had not won at Murrayfield for three years, but claimed a first Pro12 success in four attempts and keep their opponents third-bottom.
Junior Bulumakau, Josh Strauss and Alex Dunbar were the try-scorers, with Edinburgh only able to muster 12 points from the boot of Duncan Weir.
Steven Shingler inspired Cardiff Blues to victory in the other Pro12 game on Monday, scoring an early try and going on to notch 17 points in a 27-16 win over rivals Newport Gwent Dragons.
All the scoring came in the first half as the Blues came out on top in Sam Warburton's 100th appearance for the region, outscoring the Dragons by three tries to one.