Sydney FC have most improvement: Arnold Sydney FC have greater upside than any of the A-League's early pacesetters, coach Graham Arnold says. Arnold's Sky Blues remain unbeaten after holding Adelaide United to a scoreless draw on Friday night. Sydney FC, Adelaide and Melbourne Victory are all undefeated but Arnold says his outfit has more improvement to come than their rivals. "I think Adelaide are at their best," Arnold said. I think Melbourne Victory are close to their best. And I think we have got a lot to go. Arnold was rapt to take a point for their away draw against the Reds, who dominated general play but butchered several scoring chances. "If you can go out and play against a team that is playing in that type of form and very high in confidence ... and we walk away with a point and we haven't played at our best, then you have got to be happy," he said. But he said Sydney were functioning at 80 per cent defensively and just 50 per cent with the ball - though he was uncertain how long it would take to reach maximum output in all facets. "There is so much more upside for us with the ball," he said. We are going to have periods or stages up until Christmas where we will dominate teams and have a good night with the ball. And then other nights we're not going to have a great night with it because we're still a work in progress of the style that I want us to play. But defensively, you have to be strong and that is what we have worked on. Arnold was confused by a contentious moment against Adelaide when his acting captain Nikola Petkovic scored with a 35 metre free kick in the 68th minutes. The goal was disallowed by referee Alan Milliner, ruling he had not restarted play when Petkovic took the kick. "The boys said that with Petkovic's, he (the referee) pointed to halfway, he pointed for it to be a goal," Arnold said. And when the Adelaide players rushed to him, he changed his mind. That is what I have been told.