Cahill got his first start of the season, but only lasted 25 minutes after rolling in ankle in a clumsy challenge.

A rare goal by Luke Wilkshire on the hour saw Sydney leap frog the home side to take the summit, ending coach Warren Joyce's four-game winning start at City.

BREAKING: Cahill injury scare

REACTION: Where there's a Wilkshire there's a way

Mauk admitted losing Cahill was unsettling.

"You're playing all week to do certain things and when a player like Timmy goes down it disrupts the team," he told Fox Sports.

"But in saying that we had a great player coming on in Marcin (Budziński). I'm not going to use that as an excuse. We lost and it happens to every team."

Cahill was taken to hospital for scans but before that he rallied the team at half time telling them "to keep going, fighting and doing everything to keep a clean sheet," Mauk said.

"So he was in good spirits - I don't think it's too serious, I hope not. I guess we've just got to focus on next week."

The 22-year-old midfielder said the outcome was an improvement on the last time the two teams met - City going down 2-0 in the FFA Cup - but he was far from satisfied.

"Last time we were disappointing," he said. "We've been pretty good the last four games. I think tonight we probably weren't good enough on the ball.

"Defensively I thought we were pretty good and beside their goal I didn't think they really had a chance and they're the champions - that was good in terms of that - but I think we need to be much better on the ball to create chances."