A shocking moment which aired during Monday night's episode of SAS Australia went unnoticed by thousands viewers.

During the show's 'Aggression' episode, the recruits took part in the 'Murder Ball' challenge which saw them put their skills of hostility to the test against their fellow competitors.

The challenge involved groups of two pitted against each other, with one carrying a heavy medicine ball up a sand dune while the other was forced to use their aggression to snatch the ball off them.

'Aggression is the most powerful weapon a human can possess,' SAS Australia Chief Instructor Ant Middleton said.

'No punching, this isn't about going in there like headless chickens. Clashing your heads together and injuring yourselves. That's not a thinking soldier.

'This task is about using controlled aggression to take down the enemy.'

He added: 'When you go into combat, it's do or die. You fight till the death.' 

First up was AFLW player Abbey Holmes, who was pitted against actor Craig McLachlan.

Craig was tasked to carry the ball first as Abbey tried to rip it from his grip.

Without throwing any punches, the sports star wrestled and tackled her opponent to the ground, wrapping her arms around his shoulders in an attempt to make Craig lose the ball.

But as the instructors cheered for Abbey, the unthinkable happened.

The 32-year-old quickly picked up a handful of sand beneath her and threw it into Craig's mouth and eyes.

The moment was missed by many, but the SAS instructors praised the former athlete for her efforts and continued to cheer her on.

'I am a competitive beast,' Abbey said.

'I'm someone who always wants to achieve and do things 100 per cent and win.'

'If I don't win or I don't do things exactly as the DS expects, I might be disappointing them yes - but I'll also be disappointing myself,' she added.

The challenge between Abbey and Craig was ultimately called a draw, meaning neither opponents failed.

Last week, Abbey faced a horrifying near-death experience on the show, facing her fear of heights during a challenge alongside rugby union and league star Mahalia Murphy, 29.

The challenge required Abbey to scale a cliff as Mahalia acted as the belayer, aka the 'brake man', while their fellow team mates watched on.

But things took a turn when Abbey suddenly fell backwards off the cliff.

Despite listening and following instructions, Mahalia didn't have the firm grip required to safely suspend Abbey from free-falling down the cliff, leaving DAS Jay to step in.

As Abbey cried out, her fellow SAS competitors could do nothing but helplessly watch on in horror.

As DAS Jay took control of the rope, Abbey was fortunately saved from hitting the ground.

'I went down to the first ledge as instructed and then when I was told to standby I went to go like that [placing her arms out to the side]. But I fell back,' she tearfully explained.

DAS Jay then ripped into Mahalia over Abbey's brush with death, telling her that Abbey fell because she 'didn’t have f***ing hold of the f***ing rope'.

'Look at number four [Abbey],' he said to Mahalia, as a terrified Abbey replied: 'I'm good.'

SAS Australia continues Tuesday 7.30pm on Channel Seven and 7Plus