Prime Minister Jacinda Ardern and finance minister Grant Robertson's rugby rivalry

Prime Minister Jacinda Ardern and her right-hand man, Finance Minister Grant Robertson, have taken their rugby rivalry online for the opening match of the Super Rugby Aotearoa. Photos / Instagram

They're united in the halls of power, but on the footy field? Forget it.

Prime Minister Jacinda Ardern and her right-hand man, Finance Minister Grant Robertson, have taken their rugby rivalry online for the opening match of the Super Rugby Aotearoa competition.

The pair traded photos in their supporter's gear, after Robertson - a Highlanders fan - gave a shout out to his Chiefs-supporting boss.

The Otago-based Highlanders edged past Waikato's Chiefs in a nail-biting 28-27 opener at Forsyth Barr Stadium tonight.

But before kick-off Robertson tagged Ardern in an Instagram post from the stadium.

"Ok @jacindaardern how do you think your Chiefs are going to go? Awesome atmosphere at Forsyth Barr Stadium for the world first pro rugby game. #highlanders #superrugby", he wrote next to a photo of himself draped in a Highlanders scarf.

Unlike her team, Ardern wasn't about to be beaten, posting her own response on the social media platform.

"I see your Highlanders scarf @grantrobertsonmp and I raise you a Chiefs jersey. Sad to miss what I think might be one of the first professional games played in front of a stadium of people for quite sometime. I'll be watching from afar (and virtually shouting you down, Grant!)."

View this post on Instagram

A post shared by Jacinda Ardern (@jacindaardern)

There's plenty of oomph in the prime ministerial voice, but it wasn't enough to help the North Island team.

Although the Highlanders went into the break with a narrow lead, their rivals stayed in the match, taking it to a one-point game when Anton Lienert-Brown crossed the tryline with eight minutes to play.

Highlander Patelesio Tomkinson makes a break during tonight's match against the Chiefs. Photo / Joe Allison / www.Photosport.nz

Damian McKenzie then looked to have wrapped it up for the Chiefs with a drop goal two minutes before fulltime, but Bryn Gatland ended Chiefs' supporters hopes with a 40m drop goal of his own, giving the southern side a one-point victory.