With two rounds to play, a Victory win over Brisbane Roar at Suncorp Stadium on Saturday would all but guarantee it the A-League minor premiership and entry into the AFC Champions League (ACL).
But Arnold believes a win by his-second placed Sydney FC over Newcastle Jets at Hunter Stadium on Friday night will keep his side in the hunt and heap pressure on the Victory.
"Victory have one hand on the plate, but the other hand is the one with all the pressure," Arnold said.
"Pressure does funny things to teams and players."
The Sky Blues will be hoping to narrow the differential between them and Victory - seven goals in Melbourne's favour - over the final two rounds.
Arnold said all Sydney could do was worry about its own game, starting with the clash against an improved Jets side that beat Victory last week.
"What you can see is there's a lot more fight in that team, and a lot more structure to what they're doing," Arnold said of the Jets.
The Sky Blues coach said playing the fixture away didn't faze Sydney, and may even help to ease tension in a must-win game.
"Sometimes when you're in that position on the table ... it's better to play away from home, because the pressure is removed," he said.
"And they (Newcastle) haven't had too many good results at home."
Sky Blues midfielder Mickael Tavares was a strong chance to return to the side after missing last week's game against Perth with a groin injury.
"He trained fully yesterday," Arnold said. "He'll do the tactical session today then we'll make the final judgment.
"Mickael is probably 90 per cent ready to go."
