But the former Leeds and Liverpool winger, who has been in charge at the Marinos since December, says his side will have to "suffer" before they earn the right to lift the Asian Champions League trophy.
Heading into Saturday's second leg at the Hazza bin Zayed Stadium in the United Arab Emirates, Yokohama hold a 2-1 lead in the final of Asia's premier club competition.
But despite their first-leg lead from the opener in Japan, getting past opponents Al-Ain - the 2003 Asian champions who also reached the final in 2005 and 2016 - won't be easy.
"I've never been afraid of a challenge and I'm going to make sure my team's not afraid of this challenge," Kewell said as he looks to join Tony Popovic, with Western Sydney Wanderers in 2014, as Australian coaches to win the competition.
"It's going to be tough ... nothing's given for free, you have to pay for it, you have to work for it.
"We have to suffer if we want to pick up this title."
There will be celebrations in the UAE on Saturday regardless of the result.
Sheikh Mohamed bin Zayad is not only leader of the Gulf state but has been club president of Al-Ain since 1979.
His vice-president, Sheikh Mansour bin Zayed, is the owner of English Premier League club Manchester City, the founding member of the City Football Group - a worldwide stable of 13 clubs which became a minority shareholder in Yokohama in 2014.
If the Japanese team win they will participate in the 2025 FIFA Club World Cup, where they could face their EPL stablemate in the tournament, which has expanded from seven to 32 teams.
For Kewell's rivals Al-Ain, their 2016 Asian Champions League final defeat will serve as motivation.
"That's why everybody wants this trophy so bad," Al-Ain defender Khalid Al Hashemi said on the Asian Football Confederation's official website.
"I hope from the bottom of my heart that we can give happiness to everybody in our country."
Al-Ain, coached by former Argentina striker Hernan Crespo, took an early lead through Mohammed Al-Baloushi at Yokohama's Nissan Stadium on May 11, only for late goals from Asahi Uenaka and Kota Watanabe to give Yokohama a slender advantage.
"We lost against great opponents who played very well but we did have chances which we didn't put away," former Milan, Inter and Chelsea forward Crespo said.
"We have another opportunity at home and I hope it will be different."
Postecoglou coached the Marinos from 2018 to 2021, while Muscat was at the helm for two years to December 2023.
- with AAP
