The Sky Blues face a resurgent Roar side at Allianz Stadium on Sunday with Arnold's men hoping to equal a club-record of nine unbeaten matches.
With Sydney looking like a genuine title contender for the first time in five years and Roar rediscovering some of the form that earned it three championships in four seasons, Arnold is expecting an action-packed encounter.
"I had a three-year rivalry with Brisbane up at the Mariners and nothing's changed since I've come here.
"Frans Thijssen is doing a fantastic job, he's recruited well, like we did, in the Asian Cup period and both teams have gone to another level.
"So it's going to be a great clash."
After an unconvincing start to the season, Roar has gone on a five-match unbeaten run.
It began in German playmaker Thomas Broich's first game back from ankle surgery.
But Arnold says he's not the only player the Sky Blues need to be wary of.
'It's no coincidence that Thomas Broich has come back in and they're performing much better," he said.
"So we have to make sure we're at the top of our game.
"I think overall as a team they're getting back to where they were.
"They've got quality players like Broich, Mat MacKay, Henrique is always a danger, Brandon Borello is having a great season and Luke DeVere has been picked in the Socceroos so he's obviously ding something right."
But Sydney has its own dangerman in marquee striker Marc Janko.
The Austrian, who has taken the lead in the race for the golden boot with 13 goals this season, will break a league record if he scores in a seventh straight game on Sunday.
But Arnold says that's no motivation for his side.
"We prefer team records than individual records," he said.
"Marc has been on a great roll of late and I'm sure he wants to continue it.
"But we have to just concentrate on the team performance and make sure our structures are good and we play to the game plan.
"If all that comes to fruition then hopefully Marc can get the record he wants."