Munster and Ulster are both one win away from a spot in the quarter-finals of the European Champions Cup.
Munster are first up at 1pm - they host Castres at Thomond Park with a one point lead at the top of Pool 4.
A win of any kind will be enough for the Reds thanks to their head-to-head record with closest challengers Racing 92.
Thomond will be rocking on Sunday for our must-win Champions Cup clash against Top 14 high-flyers Castres!
— Munster Rugby (@Munsterrugby) January 18, 2018
Look forward to seeing you there!
Tickets available | https://t.co/X5DbEZ9z2g#MUNvCO #SUAF pic.twitter.com/mEDoP8bZYk
Irish attention then shifts to the Ricoh Arena will Ulster have a tough assignment away to Wasps who also have an outside chance of reaching the last eight.
Kick off there is at 3.15pm.
🙌 Christian Lealiifano is set for his final Ulster appearance tomorrow.
— Ulster Rugby (@UlsterRugby) January 20, 2018
Wasps v Ulster (3.15pm) is live on @btsportrugby pic.twitter.com/uS7rUXseU5
More on both games throughout the afternoon right here.