After the high of last Saturday has to decide how many players to take out of their comfort zone for the middle Autumn series clash with Fiji.
The Ireland head coach has options to work out on the back of the victory over world champions South Africa.
Farrell wants to continue to build momentum ahead of the Six Nations kick-off in February.
He also has to take into account that it is less than a year to the World Cup. Opportunities to look at potential squad members are quickly running out.
Farrell gathered 49 players together in camp before they broke off into the squads that played for Ireland A against the All Blacks XV on Friday night and the Test side that met the Springboks the following evening.
The Ireland coaches will still have got plenty out of the Friday fixture, even with so few players putting their hand up against a Kiwi outfit on a mission to inflict pain on the scoreboard and in the collisions.
Some of those involved are on the fringes of the Test set-up but a poor collective performance could be reflected in Thursday's team announcement.
Still, Farrell took the benefits from the A game. "It’s priceless for us to see how these lads deal with the week," said the 47-year-old.
"It's how they deal with the pressure, with the anxiety of coming together and not just taking the field against quality opposition, but how they transition into playing in a side that they’ve never been involved in before.
"But unless you have that experience then how do you grow? How do you learn? How do you push on?
"We all need to be put out of our comfort zones from time to time to reassess where we’re at and if we’re serious about kicking on or not.
"It’s great because we’ve now got more of an opinion going forward."
The coaches are making their minds up on players now for what's ahead and there will be chances for some to further their case this weekend.
However, hopes of giving Ciarán Frawley his first Test exposure will have to wait after he suffered a twisted knee against the All Blacks XV. Jack Crowley is in line to be the next man up.
Johnny Sexton is recovering well from a dead leg but Joey Carbery is expected to start at no 10 anyway, as he needs Test game time. His in-form Munster colleague Crowley could be poised for his Ireland debut.
Jamison Gibson-Park and Hugo Keenan made their season bow last weekend - Keenan from the start, Gibson-Park less than half an hour in - and both hit the ground running.
They need the game time against Fiji and Ireland A captain Craig Casey will be Gibson-Park's back-up. Conor Murray (groin) is injured.
Keenan could be joined in the back three again by Rob Baloucoune, who started last Saturday and is still finding his feet at Test level.
Jimmy O'Brien is in line for his first Ireland start - probably on the wing, after an impressive display at centre when he replaced Stuart McCloskey against the Boks - although Jacob Stockdale and Michael Lowry will also stake a claim.
At centre, Garry Ringrose may be rested and Bundee Aki is suspended until next week's clash with Australia.
McCloskey (arm) has made a swift recovery, Robbie Henshaw has recovered from his hamstring injury and could start. James Hume is also in contention despite a difficult Friday night.
In the pack, Finlay Bealham made great strides when he replaced Tadhg Furlong last Saturday. Furlong is expected to train after an ankle injury, but it could be Bealham and Tom O'Toole vying for the starting tighthead spot this week.
Kieran Treadwell may get a second row start but Iain Henderson is nearing a return to full fitness. In the back row, Farrell could rest some of his frontline players after a tough shift, with Jack Conan, Max Deegan and Nick Timoney hoping to benefit.
IRELAND SQUAD
Backs: Baloucoune, Blade, Carbery, Casey, Crowley, Gibson-Park, Hansen, Henshaw, Lowry, McCloskey, Nash, O'Brien, Ringrose, Sexton, Stockdale.
Forwards: Bealham, Beirne, Conan, Deegan, Doris, Furlong, Heffernan, Healy, Henderson, Herring, Loughman, Milne, O'Mahony, O'Toole, Penny, Porter, Prendergast, Ryan, Sheehan, Thornbury, Timoney, Treadwell, van der Flier.
READ NEXT:
Murray and Frawley out of series but better news for other senior Ireland stars
Martin O'Neill recalls John Delaney's reaction to him wanting Roy Keane as assistant
Seamus Power surges to top of Fed-Ex Cup rankings after another big payday
Boca Juniors game ends with 10 red cards as World Cup referee loses plot in cup final
Katie Taylor says she has had to 'sacrifice the ordinary pleasures of life' for boxing success
Get the latest sports headlines straight to your inbox by signing up for free email alerts
