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Sydney remain unbeaten and firmly among the early pacesetters after winning 2-1 away to Melbourne City on Saturday night, a victory made possible by the organisation and work-rate of the visitors at AAMI Park.
Discussing his work at the club so far after the game, Arnold pinpointed the fact the team are now defending from the front as key.
"It's not so much how they've improved from the back, it's how they've improved as a team, defending from the front," he said.
"The first line's hard to break."
It was put to Arnold that the great strides made by the Sky Blues early in 2014-15 would not have been possible with Del Piero still at the club.
"I'm enjoying watching him in the Indian Premier League," the coach said with a chuckle.
When pressed on whether or not his tactics would have worked with the ex-Juventus man still in Sydney's ranks, he said: "Yeah probably."
Asked if the rest of the team would have had to work harder to compensate for the Italian's reduced mobility, Arnold said: "Maybe he would have had to work harder."
Next up for the high-flying Sky Blues is an enticing derby clash away to Western Sydney.
With Tony Popovic's men still searching for their first win of the domestic campaign, Arnold didn't miss an opportunity to fire the first verbal salvos of what is sure to be a frenzied build-up to the game.
"They'd be hurting enormously," he said of the Wanderers.
"It's not the biggest derby, because only 18,000 can fit in, compared to ours, where it's 43-44,000. It's not that intimidating at all. We're looking forward to the occasion."