The Sky Blues have collected seven points from their first three games of the 2017/18 A-League season, but haven’t fully convinced.

Sydney’s tight defence which conceded only 12 goals throughout season has already let in four goals this term.

On the flipside, Sydney boast a wealth of attacking options in Johnny Warren medallist Milos Ninkovic, top scorer Bobo, new recruit Adrian Mierzejewski, captain Alex Brosque and super-sub David Carney.

Zullo identified rectifying their defensive issues as the key to re-discovering their best, believing they’ve got the league’s best quality in attack.

“I think there’s heaps of improvement,” Zullo said. “I genuinely believe that.

“I think physically we’re the fittest in the league.

“In terms of quality in the attacking third, we’ve shown enough already to indicate we’re head and shoulders above the rest.

“Defensively we were super strong last season.

“As a defender, we all want to improve defensively because we know that’s the last thing we need to do to get us on the right track for the rest of the season.

“We’ve already started off quite well but we feel we’ve still got so much more to give.”

On Friday night, the Sky Blues come up against Perth Glory, who were last season’s second top scorers behind Sydney.

Zullo said Glory’s dangerous attack featuring Diego Castro, Andy Keogh and Adam Taggart wouldn’t faze them, despite their leaky start.

“To be honest I don’t think it matters who we come up against,” he said.

“We expect to keep a clean sheet every game.

“That’s something that set us up well for the title last year.

“I think good teams win premierships and championships based on defence.”

Meanwhile, Zullo was unfazed by Western Sydney’s FFA Cup semi-final defeat to Adelaide United, which means there will be no Sydney Derby decider.

“Either way it didn’t change much for us,” he said.

“We were just waiting to see who we’d play. It’s Adelaide, so we’re all looking forward to it.”