The Sky Blues boss believes his players have to be wary of a wounded animal in the form of the winless Melbourne Heart
The Heart are languishing in last place on the ladder and are still searching for their first victory of the season, while the Sky Blues are in fourth spot after nine rounds.
John Aloisi's men are coming off consecutive draws against Adelaide United and Western Sydney Wanderers, while Sydney FC were on the wrong end of a 1-0 loss to Central Coast Mariners last Saturday.
"They have (got momentum) and we've watched their past two games and they showed a lot of character in both and they're obviously improving," Farina said of the Heart.
"We're under no illusions that this is a tough and dangerous game for us.
"Even though they haven't won a game yet, it's got to happen sooner or later and hopefully it's not against us."
Adding to Farina's concerns is the return of Harry Kewell who made a successful comeback from injury off the bench against the Wanderers last weekend.
"I think it's a huge lift to have someone the calibre of Harry available," Farina said.
"Whether he's ready to start or come off the bench like he did last week, he's a great inclusion for them. I think as you say he'll lift the side and they're travelling a lot better."
However, the likely return of skipper Alessandro Del Piero (hamstring) and Brett Emerton (leg) is a boost for the Sky Blues.
Farina was upbeat about the pair's prospects of a return on Friday, with a decision on their availability to be made on Saturday.
"We've still got two days to get through but at this stage they're both available," he said.
"It's always nice when you're getting players back, especially players of their calibre.
"He (Del Piero) has obviously been doing training, the boys had the day off on Thursday but he was in with a number of others training.
"At this stage he's looking all right but until we get him in training with the squad and see how he is we won't make a decision until then."
The coach added when asked what changes are needed after the Mariners loss: "As I said after the game we were our own worst enemy.
"We had a lot of possession but we turned over a lot of possession with just bad passes or bad decision making and you'll have bad games like that but I'm expecting a big improvement in that area.
"The effort was there, we ran again for 90 minutes but just the simple things we didn't do as well as we can."