For all the barbs thrown leading into the biggest Sydney derby to date, it was a sobering and emotional message from Sydney FC coach Graham Arnold that motivated his players to a 4-0 win.

There was no reminder of 'hate' towards Western Sydney Wanderers – such as those captain Alex Brosque's spoke about during the week – only one request from a child battling cancer.

Young Sydney FC fan Gabriel Cipriano sat next to Arnold in the dugout during a match last year and sent the coach a plea to the players before the derby at ANZ Stadium. He couldn't attend the match but was watching from home, where he told Arnold how much a win in the derby would help his brave fight against the illness.

"I had a beautiful text this morning from a kid, Gabe, who sat next to me on the bench last year," Arnold said.