"The biggest game is 2005," Arnold said of Australia's famous play-off win over Uruguay in Sydney where he was an assistant coach to Guus Hiddink.
"I pretty much put this game alongside that."
A win over Peru at the Ahmad bin Ali Stadium in Qatar on Monday (0400 Tuesday AEST) would be the crowning achievement of a tenure which has increasingly come under criticism since the Socceroos' campaign stalled last October.
Just one win from the last seven matches of the group stage of Asian qualifying cost Arnold's team a shot at an automatic place in Qatar 2022 and had many tipping the 58-year-old would be sacked before this month's play-off matches.
Football Australia however stood by Arnold and the team is now one win away from a fifth-straight World Cup after defeating the United Arab Emirates 2-1 last Tuesday.
The challenge that lies ahead however is another level.
World No.22 Peru may not be the most star-studded squad from South America but they boast a coach in Argentinean Ricardo Gareca who emulated Hiddink's achievements by qualifying for Peru's first World Cup since 1982 in a play-off win over New Zealand five years ago.
At Russia, Peru claimed a 2-0 win over the Socceroos when the two nations met in the group stages and, while both teams have undergone changes since that game in 2018, la Blanquirroja (the white-and-red) are most people's favourites to advance at Australia's expense.
"I'm at the age now where it's not about me at all," Arnold said.
"It used to be more about me years ago, but not now. I'm just here to help the staff and the players and the nation to again achieve something great.
"It's been a tough, tough period for myself and that - going through this pandemic, what we've been through, and the fact that I've missed the last two camps because of COVID but all that's in the past.
"It's one game now.
"It's 90 minutes.
"It's a life-changing moment for these boys and that's all I'm focused on, is helping the boys and making sure that they're ready to go."
Defender Trent Sainsbury (knee) is pushing hard to feature after missing the UAE win, but it's looking increasingly unlikely striker Adam Taggart's thigh niggle will keep him sidelined.
If Sainsbury is cleared to play, Arnold will have to oust either Bailey Wright or two-gamer Kye Rowles from the heart of his defence or add the experienced 30-year-old to his substitute's bench.
Melbourne Victory fullback Jason Davidson (hamstring) is almost certain to be ruled out after only doing light duties at training on Saturday.
While Monday's game will be played at a neutral ground, approximately 12,000 Peruvian fans have descended on Doha in a number that will dwarf the 500 or so Australian supporters expected to attend.
Not that the huge Peru support is fazing Arnold.
"That'll make us even more proud when we send them all home disappointed."
