Following last week's disappointing showing against the Japanese team, the head coach told his Ireland squad to improve their performance.
The team responded right away.
Ireland had faded in the final stages against the All Blacks and required most of the match to find their rhythm versus their Asian opponents.
Nevertheless, facing Australia, they began powerfully, with the talented back excelling brightest during a comprehensive triumph that marked Ireland's finest performance of the season.
In his debut test match start at the number 15 position, Hansen scored a three tries, contested excellently for high balls and performed outstandingly against the nation of his origin.
"You know, I've had a fairly difficult run with injuries really," Hansen stated.
"I longed for being in this squad, I understand there's much talk about me not exactly being born here and I wasn't raised here, but I adore this group and this feels like home.
"Whenever I have to represent for the national team it's a honor, if you don't put in a good showing you may not receive that privilege again.
"My entire approach this week was to take the field and perform what I can do."
Following twenty-eight caps on the flank, Hansen was entrusted the full-back role for the initial time with several teammates injured.
In his case, it was essentially a matter of picking up where he finished during the summer.
The 28-year-old had been in excellent form before physical issues disrupted his dream of making the Test team.
After returned recently, he suffered a lower body injury that ruled him out for previous fixtures.
Farrell had suggested that the player was especially motivated and these proved not hollow words as the ex- provincial player gave his manager a positive selection headache for upcoming matches.
"So my first reaction were, 'You need to perform excellently in those different colored boots!'," commented the coach, referring to the player's decision to sport different boots.
"Actually I thought that was fitting but apparently Hansen just did that personally anyway. So he's attracted attention to himself before he's even begun.
"I told to him before the game, 'Good athletes don't need excuses, they can get on with it and just play naturally, you can win the player of the game if you choose,' and he responded, 'Yes, I concur.'
"Therefore he's that kind of player, he trains well, he's got a excellent approach to get across his detail and thus that's why he slotted straight into the team and he was able to perform naturally due to that."
The player's performance also earned praise from the opposing manager, who stated he was the "exceptional opposition player" on the night.
"I thought he was outstanding, his knowledge showed to the fore," commented the former national coach.
"Regrettably, Mack was probably the standout Australian player on the pitch. He's got a excellent skillset and he's such a strong competitor."
When asked about what makes Hansen a strong fit at full-back, Farrell added: "Showing up in the middle of the pitch is a trait that he demonstrates from the wing anyway, but I imagine he's better in position for that frequently.
"His high ball play was brilliant, don't you think? I believed we persisted of executing the correct thing and that was putting the ball again on them to secure field position.
"Why that was the correct strategy to do is because it's the players of Hansen who was getting the possessions returned, and other teammates, so [it's] pretty pleasing."
Beyond the star performer, there were numerous encouraging aspects for Farrell.
Sam Prendergast was excellent on his return to the fly-half position, the scrum and throw-in functioned effectively and different player did not look out of place in his debut appearance in the front row.
But possibly most satisfying for the manager was the team bookending the game with multiple strong spells.
Hansen's initial two scores occurred in the first eleven moments while additional players registered in the final stages after the other team had crossed, guaranteeing the home team concluded on a high.
"I thought we truly performed freely and approached the match straight from the word go," said Farrell.
"The way we managed various aspects during the match, especially the opposition coming back just before the break and regathering ourselves and giving a display like we achieved in the second half, I believed as far as territory and being across most of our game in that second half was truly pleasing."
The strength of the Springboks are awaiting for Ireland, in what might be considered as an unofficial conclusion to last year's tied two-Test contest on rival soil.
The coach's side will need to attain another standard to defeat the back-to-back title holders, but the recent victory of the Wallabies was a significant step in the correct direction after an uninspiring beginning to their fall schedule.
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