Victory over Shandong Taishan this month saw Kewell lead the J.League outfit into the Asian Champions League semi-finals for the first time, surpassing the records of Ange Postecoglou and Kevin Muscat in the club's pursuit of a first continental title.
That progress is an early riposte to those who questioned Kewell's ability to follow his two J.League-winning compatriots at the helm of one of Japan's most successful clubs.
Former Marinos coach Kevin Muscat celebrating with his players after a J.League win. (AP PHOTO)
"The attitude of the players has been excellent, with the willingness to learn a slightly new style," Kewell, who won the UCL with Liverpool in 2005, says of his early days with the five-times J.League champions.
"I'm not saying I've had to scrap it from the start because they've got such a great base already, especially from the previous two managers.
"It's been quite easy to implement my ideas."
Kewell is the third Australian in succession to take charge of the Nissan-backed club, who are also part-owned by City Football Group, having joined despite limited front-line coaching experience since ending his playing career in 2014.
Underwhelming results in the lower tiers of English football meant he was a surprise appointment to follow in the footsteps of Postecoglou and Muscat, who led the club to the J.League title in 2019 and 2022 respectively.
Neither, though, were able to deliver continental success and Marinos are now one step from the Asian Champions League final.
Former Celtic assistant Harry Kewell poses with former manager Ange Postecoglou in Sydney. (Dan Himbrechts/AAP PHOTOS)
They take on South Korea's Ulsan Hyundai on April 17 and 24, and victory would see them meet either Saudi Arabia's Al-Hilal or Al-Ain of the United Arab Emirates in the final.
"What I look for in my team is an understanding between each player," Kewell says of his coaching style.
"A communication, a realisation that if someone is in your position you can easily come out of that position and make a forward run or make a different movement and that player then realises he can slip into another role.
"I look for smart players, players to be able to realise situations and be comfortable that if they are put in that (situation) they can handle it."
Kewell's approach means his impact has not only been felt on the continental stage.
While Marinos are ninth in the 20-team J.League standings, the Australian's team trail Machida Zelvia by four points, having played one game fewer than the early leaders.
"I want to see this team change, I want to see them make decisions on the park which then we can analyse and then we can make changes," says Kewell.
"They've already created things where I've gone: Wow, I can work with that. They're improving every day, which I'm proud about. As far as where they can end up: Who knows?"
