The strange part is Pivac's first uncapped match at the Welsh helm comes against Gatland, who, alongside Robbie Deans, leads the Barbarians team featuring Matt Duffie, Bryn Hall and Shaun Stevenson.
This week is likely to be as much about Gatland's final, final farewell as it will be the start of Pivac's new era.
In many ways, this weekend represents the symbolic passing of the baton. Only then will Pivac's term truly begin.
As he prepares to return home and take the reins at the Chiefs, Gatland has officially severed ties with Wales after 12 years in charge. Yet his overbearing shadow remains.
Not merely figuratively this week, either.
Behind the scenes Gatland may have been more welcoming but his comments after Wales lost to the All Blacks and finished fourth at the World Cup that it would break his heart if the Welsh "went back to the doldrums" in his absence hardly laid out the cake and tea for Pivac.
Gatland's extended tenure included four Six Nations titles – three Grand Slams – and the first stint as the world's top ranked side. He was always going to be a difficult act to follow.
There was, surely, no need for him to underline the point.
It could be an odd week for Gatland.
Pivac will settle into Gatland's old digs at the Vale Resort on the outskirts of Cardiff.
Gatland will then sit in the away dressing room at the Principality Stadium, a venue he holds many fond memories.
Pivac is a different coach, different person, to Gatland.
For starters most of his coaching vision was shaped in the Southern Hemisphere.
Pivac has shown his hand, somewhat, in attempting to break from Gatland's grasp.
His new coaching team includes Stephen Jones (attack), Byron Hayward (defence), Jonathan Humphries (forwards), Sam Warburton (technical advisor on defence and the breakdown) and Martyn Williams (team manager).
That management group appears a solid blend of old and new. Warburton is a particularly savvy appointment in that the voice of the former Wales and Lions captain will offer a recent connect to the largely-established playing group.
Pivac wasted no time signalling intent, and fuelling controversy, by including former Crusaders outside back Johnny McNicholl and Hurricanes midfielder Willis Halaholo in his 35-man squad for the Barbarians.
Halaholo has since withdrawn after rupturing his ACL which rules him out for the next nine months.
Those selections, though, confirm Pivac will adopt much more attacking ambition than has been evident under Gatland.
Prior to the World Cup, Wales won this year's Six Nations largely due to their supreme defence. It was a similar story throughout Gatland's term – Wales earning respect through their resilience more than anything else.
They were not a side that inspired with flamboyance or creative endeavour. In the last Six Nations they scored 10 tries in five tests, tied with Italy for the joint-lowest.
Pivac's intent to attack more brings risk in the northern climate but, potentially, more rewards too.
It will be fascinating to watch how he encourages playmakers Gareth Anscombe and Dan Biggar, who is beginning to thrive with more freedom at Northampton under Chris Boyd, to have a crack and back their natural flair.
There is, however, no escaping Pivac's difficult task.
When Gatland assumed control Wales were ranked 10th and he parts with them in fourth.
Comparisons are inevitable. These are the standards the unforgiving Welsh public will now expect Pivac to at least maintain.
Following this Barbarians match Pivac embarks on what promises to be a challenging Six Nations, starting in early February, which England will be expected to win.
Pivac's first overseas tour in July is then to none other than New Zealand, where Wales are scheduled for two tests against the All Blacks.
This Barbarians match is something of a free hit, the result largely irrelevant and the pressure off.
But as Pivac becomes the latest installment in the ever-expanding list of Kiwi coaches to lead Wales, Gatland's presence this week is a reminder of the burden he will bear.
