Hot on the heels of Ireland's Grand Slam success, Munster, Leinster and Connacht resume their race to Bilbao.
In the Champions Cup, Johann van Graan's Reds host Toulon at a sold-out Thomond Park today (3.15), while champions Saracens take on Leo Cullen's Leinster at a close-to-capacity Aviva Stadium tomorrow (3.30).
Connacht kick things off this lunchtime (1.0) as they welcome Gloucester to the Sportsground for their Challenge Cup quarter-final.
For Munster and Leinster, it is an opportunity to return to the stage at which they exited the competition last season and a chance to claim the scalp of a European thoroughbread while doing it, as Saracens and Toulon have won the last five installments between them.
Simon Zebo has given the Thomond Park faithful a significant boost by declaring himself fit to play alongside Andrew Conway and Rory Scannell who also overcame their injury issues to take their place in the starting XV.
The Munster full-back, who moves to Racing 92 at the end of this season, is fully aware of the significance of this game.
"The history of Munster is linked to this competition, we obviously know that this is the 10th anniversary of the last European title," he said. "And it makes us even more hungry. Since then, the club has changed a lot. Be it the staff, the players, the training centre.
"So we want to write our own story. This season, we have an experienced team, made up of good players but also young players with good qualities, who should have their chance."
Toulon arrive at Thomond Park with a side packed with international talent as coach Fabien Galthie recalls Springbok Duane Vermeulen, All Black Ma'a Nonu and France out-half Francois Trinh-Duc to his side.
There is no place for New Zealand centre Malakai Fekitoa who will be asked to make an impact off a strong bench.
Leinster, meanwhile, recall a host of Grand Slam heroes including Johnny Sexton and Rob Kearney but there is no place for Seán O'Brien who has not recovered from his shoulder injury in time for their meeting with the holders tomorrow.
That means Australia international Scott Fardy moves to blind-side flanker to allow James Ryan and Devin Toner to link up in the second-row as Leo Cullen picks two back-rows on his bench in Rhys Ruddock and Max Deegan.
Leinster were left ruing a slow start in their semi-final loss to Clermont in Lyon last season and captain Isa Nacewa wants them to learn the lesson of that game.
"How we start games and how we try to build pressure on teams, reviewing that game was tough," he said.
"There were fundamental errors which let them into the game. You just can't afford that, not at top end rugby, not in quarter-finals.
"We've built each week, even through the Six Nations campaign, trying to figure out ways to manage the game.
"That was one of our biggest learnings this season."
Victory for Leinster would secure a home semi-final against the Scarlets after they overcame La Rochelle in Llanelli last night, while the winners of Clermont's meeting today with Racing await Munster or Toulon.