Thrown in the deep in at Ellis Park, the most intimidating of venues in Johannesburg where 62,000 feels like double that, Sopoaga helped steer the All Blacks with two penalties, three conversions and a generally composed display in the 27-20 win in 2015.
This was no straightforward assignment. It happened to be Sopoaga's test debut, an audition, and the All Blacks had to survive a second half yellow card to Sam Whitelock. And yet he looked nothing but at home throughout; never once overawed.
On this night, Sopoaga gave the All Blacks a clear indication he had the character and could be trusted at test level.
That same season Sopoaga guided the Highlanders to their first Super Rugby title. But his one start for the All Blacks wasn't enough to force his way into the 2015 World Cup squad with Carter, Barrett and Colin Slade preferred.
Further patience was needed long after Carter's post World Cup exit as Barrett and Cruden duked it out for the starting role.
Cracking the All Blacks is, naturally, a dream for anyone but touring life is not as glamorous as widely assumed if you're not playing regularly. Long haul flight to training field to hotel room can become frustrating if you find yourself largely on the outer of match-day squads. Most of last year as third-ranked No 10 this was Sopoaga's lot. Not that he ever complained.
Whether in the backyard or at Twickenham, every athlete wants the chance to perform.
Ten of Sopoaga's 11 tests have come from the bench. Last year he played 82 minutes in five tests; this year slightly more with 106 minutes from the same number of matches.
He is much more valuable than those figures suggest but with a player of Barrett's ability running the cutter, nabbing game-time is always difficult.
Cruden's departure to France after the British and Irish Lions series opened the door further, as the first five-eighth role became a two horse race.
With Barrett having an off night in New Plymouth against the Pumas this month, Sopoaga stepped up when it mattered to deliver an influential outing.
In 30 minutes he calmly slotted kicks from the sideline and made sharp decisions with ball in hand. He arrived with the All Blacks under pressure, and showed authority to push them home with comfort.
If the All Blacks had any doubts about leaving Barrett out of the trip to Argentina next week and handing Sopoaga the reins, they were quashed in Taranaki.
The only question now is how they handle Sopoaga's cover. Damian McKenzie has started the past four tests at fullback but, in Buenos Aires, will be required to also provide playmaker back-up. He could do that from fullback, or from the bench, with David Havili possibly given his first start.
Sopoaga's second start carries great importance. The 26-year-old, who moved south from Wellington to establish his credentials, is now New Zealand's second-choice No 10. He needs time in the saddle to grow his game and confidence.
If Barrett falls over he could well be starting the next World Cup knockout match.
The team he directs next week will be very different from two years ago, with Dane Coles, Kieran Read, and Aaron Smith the only starting survivors from Ellis Park making the trip to Argentina. Back then, Sopoaga had Ma'a Nonu and Conrad Smith's experienced heads outside him. This time it could be Sonny Bill Williams/Ngani Laumape and Anton Lienert-Brown.
But with the added inspiration of the imminent arrival of his first child, and based on his first test start, Sopoaga should again have no troubles.
