After last week's disappointing showing against the Japanese team, the head coach challenged his Irish team to improve their game.
The team listened immediately.
Ireland had faded late against New Zealand and taken considerable time to get going versus Japan.
However, facing the Wallabies, they began strongly, with Mack Hansen shining most prominently during a comprehensive triumph that marked Ireland's best performance this year.
In his first international start at full-back, Hansen registered a hat-trick, competed brilliantly for aerial challenges and performed exceptionally against the country of his origin.
"Look, I've had a fairly challenging run with fitness issues honestly," the athlete commented.
"I missed being in this team, I know there's considerable talk about me not exactly being raised here and I wasn't raised here, but I love this group and this feels like family.
"Whenever I get to play for Ireland it's a privilege, if you fail to deliver a good showing you might not get that opportunity again.
"My whole focus this period was to take the field and perform what I could do."
Following twenty-eight caps on the wing, Hansen was entrusted the full-back role for the first time with multiple teammates injured.
In his case, it was essentially a case of picking up where he finished during the summer.
The experienced player had been in superb form before injury disrupted his aspiration of making the international team.
Having returned recently, he developed a lower body problem that made him unavailable for earlier matches.
The coach had indicated that Hansen was especially motivated and these proved not empty statements as the ex- provincial player gave his manager a welcome team dilemma for upcoming matches.
"Well my first reaction were, 'You need to play well in those different colored shoes!'," said Farrell, referring to Hansen's decision to sport mismatched boots.
"Actually I thought that was appropriate but apparently Mack just did that himself regardless. So he's attracted notice to himself before he's even started.
"I said to him before the game, 'Excellent players don't need excuses, they can perform and just be themselves, you can get the player of the game if you choose,' and he responded, 'Yes, I agree.'
"Therefore he's that type of player, he trains well, he's has a great attitude to understand his detail and thus that's why he slotted straight into the team and he was capable to perform naturally because of that."
The player's performance also earned praise from the opposing coach, who stated he was the "standout opposition performer" on the evening.
"In my view he was outstanding, his knowledge was evident to the front," said the former national manager.
"Unfortunately, Mack was probably the standout opposition player on the pitch. He's got a excellent ability and he's such a good contender."
Pressed about what enables the player a strong fit at the number 15 position, the coach added: "Showing up in the middle of the pitch is a trait that he demonstrates from the flank regardless, but I imagine he's better in place for that frequently.
"The player's high ball work was excellent, don't you think? I believed we persisted of executing the correct approach and that was placing the possession again on them to secure territory.
"Why that was the right thing to do is because it's the players of Hansen who was securing the possessions returned, and other teammates, so [it's] pretty pleasing."
Outside the star performer, there were numerous encouraging aspects for Farrell.
Another player was excellent on his comeback to the fly-half position, the set piece and line-out functioned effectively and another teammate did not appear out of place in his debut start in the forwards.
But perhaps more satisfying for the manager was Ireland bookending the match with two impressive spells.
Hansen's first two scores occurred in the first eleven minutes while other players scored in the closing exchanges after the opposition had scored, guaranteeing the Irish team finished on a positive note.
"I thought we really performed freely and attacked the game straight from the word go," said the coach.
"The way we handled various elements throughout the game, particularly them coming back just before the break and regathering ourselves and producing a performance like we did in the second half, I believed as far as territory and being across the majority of our game in that later period was truly satisfying."
The might of South Africa are next up for the team, in what might be viewed as an unofficial conclusion to last year's tied two-Test series on opposition soil.
The coach's side will require to attain a higher level to defeat the back-to-back world champions, but Saturday's defeat of the Australian team was a important advancement in the correct direction after an uninspiring beginning to their autumn schedule.
A seasoned betting analyst with over a decade of experience in sports wagering and financial risk management.