Thirteen-man Western Force have scored a penalty after the final siren to secure a remarkable 21-18 win over Moana Pasifika at HBF Park.

Scores were level at 18-18 in Saturday night's match when the Force had Ollie Callan red carded in the 73rd minute and Siosifa Amone also then sent off with a yellow three minutes later.

But instead of wilting under the numerical disadvantage, the Force pulled off a series of clutch plays at the death to secure the win in front of 6497 fans.

Scrumhalf Issak Fines won a crucial penalty at the breakdown to give the Force good field position, and although Bryce Hegarty's 45-metre penalty attempt in the 79th minute missed, the home side kept pushing.

A smother from Tim Anstee put Moana under the pump and forced a knock-on error, and the Force won a scrum penalty after the final siren.

Hegarty nailed the penalty from eight metres away straight in front to secure the win. 

The result was in stark contrast to last week, when the Force were pumped 71-20 by the Queensland Reds. 

The Force leaked 10 tries against the Reds, and it took Moana just 28 seconds to touch down on Saturday night in an ominous sign.

The dazzling play started with a dribble from Moana's defensive 22 and was followed by a series of sharp passes to allow Fine Inisi to score.

The scoreboard read 15-6 in the 25th minute when Moana hooker Samiuela Moli touched down from a rolling maul.

A quick tap from stand-in Force captain Jeremy Thrush in the 35th minute proved to be a genius move.

Moana prop Sueten Asomua was in an offside position, but he laid the tackle anyway fearing Thrush would crash over.

The cynical foul earned Asomua a yellow card, and Force hooker Folau Fainga'a scored on the very next play from a rolling maul. 

Moana lock Mike McKee was given a 20-minute red card in the 46th minute for his no-arms tackle that resulted in a head clash with Folau Fainga'a.

Scores were level in the 61st minute when the Force swung it wide after a rolling maul and George Poolman touched down in the corner.

Hegarty missed the sideline conversion attempt, and the Force were down to 14 men when Callan was yellow carded in the 73rd minute for a no-arms tackle that resulted in his shoulder colliding with his opponent's head.

That card was later upgraded to red, and Amone joined him on the sidelines a few minutes later for a high hit.

But with their backs against the wall, the Force found a way to win the match. 

Force 21 (Folau Fainga'a, George Poolman tries; Bryce Hegarty 3 pen, Bryce Hegarty con) Moana Pasifika 18 (Fine Isi, Samiuela Moli tries; Lincoln McClutchie 2 pen, Lincoln McClutchie 1 con) HT: 13-15

FORCE (1-15): Tom Robertson, Folau Fainga'a, Santiago Medrano, Felix Kalapu, Jeremy Thrush (c), Tim Anstee, Ollie Callan, Rahboni Warren-Vosayaco, Ian Prior (vc), Bryce Hegarty, Toni Pulu, Hamish Stewart, Bayley Kuenzle, Manasa Mataele, Chase Tiatia

RESERVES: Tom Horton, Angus Wagner, Siosifa Amone, Ryan McCauley, Jackson Pugh, Issak Fines-Leleiwasa, Nikolai Foliako, George Poolman

MOANA PASIFIKA (1-15): Abraham Pole, Samiuela Moli, Sueten Asomua, Alex McRobbie, Mike McKee, Miracle Faiilagi, Solomone Funaki (c), Lotu Inisi, Ereatara Enari, Lincoln McClutchie, Anzelo Tuitavuki, Danny Toala, Fine Inisi, Timoci Tavatavanawai, William Havili

RESERVES: Luteru Tolai, Ezekiel Lindenmuth, Isi Tu'ungafasi, Potu Leavasa, Jonah Mau'u, Manu Paea, Henry Taefu, Lukas Ripley

Referee: Jordan Way