Arnold's place in Australian football folklore is already secured after leading the Socceroos on an inspired run to the round of 16 in 2022 where they pushed eventual champions Argentina all the way.
But four years on from Redmayne's penalty heroics in a qualifying play-off against Peru, the 62-year-old faces what is arguably the biggest challenge of his coaching career on Wednesday (2pm AEDT) as he attempts to guide Iraq to their first World Cup in 40 years.
"Before I took the job, I got told it was probably one of the toughest jobs in the world," Arnold told AAP.
"Iraq hasn't qualified for a World Cup for 40 years, it's a big challenge with a lot of pressure and they are a nation of 46 million that are obsessed with football."
Arnold would become the first Australian coach to qualify for a men's World Cup with two different nations if the Lions of Mesopotamia beat Bolivia in Monterrey, Mexico.
He does not speak Arabic but clearly understands the enormity of what could happen for Iraq if they can qualify for their first World Cup since 1986.
"I remember how great it was when we qualified in 2005 with the Socceroos, and the impact it can have on the country," Arnold said.
"In Iraq, they all bleed the one blood and they are so passionate for the game.
"Over the years that I've coached or played against Iraq, they've always been a bloody hard team and you're thinking, why haven't they qualified for 40 years?"
Conflict is one obvious answer to explain Iraq's absence from the World Cup, as is the interference of Saddam Hussein's son Uday, who was president of the country's Olympic committee and was accused of torturing footballers.
Four years after the illegal US-led invasion of 2003 that deposed Hussein, Iraq won the 2007 Asian Cup but that proved to be a false dawn.
Arnold's side - placed on a social media ban by their coach - beat the UAE to get to the play-offs with a penalty in the 17th minute of second-half stoppage time sparking nationwide celebrations.
It has already given the coach a taste of what taking Iraq to a World Cup would look like.
"In the 10 months since I've been in the job, I reckon seven of them I've been in Baghdad because I wanted to get to know the culture," Arnold said.
"I can't go anywhere and have no social life because wherever I go I get mobbed - everyone wants photos and they just run towards you.
"I saw footage of the scenes in Baghdad (after the UAE win) where they're all marching the streets and waving the flag and celebrating.
"The emotion of that win was huge and after the game was over, I had to say that we haven't qualified yet.
"These players are so passionate to do it for their country."
