Moana Pasifika have claimed their maiden Australian scalp with a shock 32-22 Super Rugby Pacific win over the Brumbies in Auckland.

The competition newcomers and cellar dwellers overcame the early dismissal of inspirational captain Sekope Kepu to power to just their second win of the season at Mt Smart Stadium.

The deflating defeat, following the Chiefs' 35-34 win over Fijian Drua earlier on Saturday, also cost the Brumbies fourth spot on the ladder heading into next week's finals.

The Brumbies will host either the Hurricanes or the NSW Waratahs in a sudden-death quarter-final next Saturday night in Canberra.

Dan McKellar's side will need to lift their game following three straight losses and easily their worst performance all year.

"It's pretty disappointing from our end. We were probably out-played, probably out-enthused," said Brumbies captain Allan Alaalatoa.

"So it's not great learnings for us. The bright side is we get another opportunity next week in the finals.

"We just need to regroup, stay connected and make sure we learn from tonight."

Elementary errors and ill-discipline cruelled the Brumbies against an inspired Moana outfit.

The Brumbies had little respect for the ball, made poor decisions, kicked out on the full from open play and then failed to find touch when trying to.

It was sloppy stuff and Moana made them pay, despite Kepu being red-carded in only the ninth minute for a high tackle on Brumbies winger Andy Muirhead.

The Brumbies wasted little cashing in on their one-man advantage with Connal McInerney finishing off a driving maul and Noah Lolesio converting for a 7-0 lead.

But against the odds, Moana crossed twice with a player short, first through fullback William Havili and then Joe Apikotoa powered over from an unstoppable maul.

When Christian Leali'ifano slotted the conversion, suddenly Moana led 12-7.

Worse was to come for the Brumbies, with the visitors reduced to 13 men after McInerney and flanker Jahrome Brown were both yellow carded in the space of two minutes either side of Moana being awarded a penalty try on the stroke of halftime.

Desperate to soak up time and take any points on offer while down on troops, the Brumbies resorted to a drop goal from Lolesio early in the second half to reduce the deficit to 19-10.

The visitors survived the 10 minutes with only 13 players unscathed but a 51st-minute penalty to Leali'ifano restored Moana's 12-point buffer.

The Brumbies turned the screws at the set piece to claim another try from their deadly driving maul, this time to replacement hooker Lachie Lonergan.

But despite camping on Moana's line, the Brumbies couldn't find the try they desperately needed to stay in the game.

Replacement half Ryan Lonergan spilling the ball after taking a quick tap instead of a gift three points in front of the posts that would have pulled his side to within a converted try typified the Brumbies' off night.

Moana sealed the Brumbies' fate with their fourth try five minutes from time through Lotu Inisi.

Moana Pasifika 32 (Tries: William Havili, Joe ‘Apikotoa, Lotu Inisi, Penalty Try. Cons: Christian Leali’ifano 2 Pen: Christian Leali’ifano 2) Brumbies 22 (Tries: Connal McInerney, Pete Samu, Lachlan Lonergan. Cons: Noah Lolesio 2 Drop goal: Noah Lolesio) HT: 19-7

MOANA PASIFIKA: 15 William Havili 14 Solomone Kata 13 Levi Aumua 12 Danny Toala 11 Timoci Tavatavanawai 10 Christian Leali'ifano 9 Jonathan Taumateine 8 Henry Time-Stowers 7 Alamanda Motuga 6 Solomone Funaki 5 Samuel Slade 4 Mike Curry 3 Sekope Kepu © 2 Ray Niuia 1 Abraham Pole
Replacements: 16 Samiuela Moli, 17 Ezekiel Lindenmuth, 18 Joe ‘Apikotoa, 19 Sione Tu’ipulotu, 20 Lotu Inisi, 21 Manu Paea, 22 Fine Inisi, 23 Anzelo Tuitavuki

Brumbies: 15 Tom Banks 14 Tom Wright, 13 Len Ikitau 12 Irae Simone, 11 Andy Muirhead, 10 Noah Lolesio, 9 Nic White, 8 Pete Sami, 7 Jahrome Brown, 6 Tom Hooper, 5 Nick Frost, 4 Darcy Swain, 3 Allan Alaalatoa, 2, Connal McInerney 1 Scott Sio.

Replacements: 16 Lachlan Lonergan, 17 James Slipper, 18 Sosefo Kautai, 19 Cadeyrn Neville, 20 Rory Scott, 21 Ryan Lonergan, 22 Rodney Iona, 23 Hudson Creighton

Referee: Mike Fraser
Assistant referees: James Doleman, Jono Bredin