Leinster and Connacht will welcome back their Six Nations heroes this week as they go in search of European glory.
att O'Connor stepped up preparations for Saturday's Champions Cup quarter-final clash against Bath by holding a mini-camp in Wicklow yesterday as he looks to integrate his sizeable Ireland contingent into the squad.
The Australian's challenge is to ensure Rob Kearney, Devin Toner, Sean O'Brien, Jamie Heaslip, Jack McGrath and Mike Ross can adapt to their provincial surrounds quickly after being controversially rested for last weekend's draw with Glasgow, while Connacht coach Pat Lam will be hoping Robbie Henshaw's return can lift his troops for their Challenge Cup visit to Gloucester.
O'Connor also must find the right blend in his match-day 23 to overcome a Bath side who also rested their England contingent for their facile win over London Welsh on Sunday, with Cian Healy, Sean Cronin and Luke Fitzgerald pushing for inclusion after impressing off the bench last weekend.
Kearney, Toner, O'Brien and Heaslip would appear to be automatic starters, while McGrath will certainly come into the match-day 23, but Ross is left hoping his experience and form for Ireland can dislodge either Marty Moore and Tadhg Furlong from the squad after they were picked ahead of him for the crucial January group games.
Apart from getting his front-row right, the main challenges for O'Connor is composing the correct back-three, back-row and centre partnership after going more than two months since last having a full squad to choose from. He also has a call to make in the second-row, with Kane Douglas expected to be available.
The return of the elder Kearney brother will see him at full-back, with his brother Dave battling Fergus McFadden, Zane Kirchner and Fitzgerald for the wing slots, with Fitzgerald also an option to wear the No 13 jersey.
However, O'Connor could stick with Samoan rugby league convert Ben Te'o, who is still adapting to the 15-man code but has added real physicality and offloading ability to the Leinster midfield alongside Ian Madigan.
In the back-row, O'Connor must choose between Shane Jennings, Jordi Murphy, Dominic Ryan and Jack Conan for the No 6 jersey if he restores Ireland heroes O'Brien and Heaslip to his side as expected.
Murphy would appear to be the front-runner after scoring a try when starting on the blindside last weekend, but Jennings' leadership and experience will work in his favour.
Leinster's reward for victory over the English side would be an away semi-final against Toulon in Marseille's Stade Velodrome or Wasps in Brighton's AmEx Stadium on the weekend of April 18/19.
Meanwhile, Henshaw's return to the Connacht squad comes just in time for Lam, who is likely to be without centre Dave McSharry for the rest of the season after he strained his posterior cruciate ligament.
Eoin McKeon suffered a concussion against Munster and is considered doubtful for Friday, while youngster Conor Finn is undergoing scans on the knee injury incurred on his debut.
On the domestic front, the western province are locked in a three-way battle for sixth place in the Pro12 and an automatic qualification spot in the Champions Cup.
Pat Lam's side yesterday had their alternative path to the top competition confirmed, with the tournament organisers outlining the process for the play-offs yesterday.
Should Connacht finish seventh, they would play the seventh-placed team in the Aviva Premiership on Saturday, May 23.
If the Challenge Cup is won by an English side not already qualified, they would replace the seventh-placed team with the winners facing off against the seventh-placed team in the French Top 14 a week later.
Connacht were yesterday boosted by two new contract extensions as hooker Jason Harris-Wright and second-row/flanker Andrew Browne penned fresh one-year deals.