Adelaide goes into Saturday's game against Sydney at Allianz Stadium having already beaten the Sky Blues at their home venue three times this season.
But Arnold noted on Thursday that his "Sydney Mark II" team has collected more points than any other club since losing a handful of starting players to season-ending injuries.
He will also have defender Sebastian Ryall, midfielder Terry Antonis and marquee striker Marc Janko back available for selection this weekend.
"If I am scared of Adelaide, I'm more scared about the fact that I've got to select 11 out of 22 players and I've got to disappoint players," Arnold said.