Fabio in fitness battle

Sydney FC defender Fabio will need to pass a late fitness test if he is to line-up for the Sky Blues' clash with Perth Glory at ANZ Stadium on Sunday.

Sydney FC defender Fabio will need to pass a late fitness test on Saturday if he is to line-up for the Sky Blues' clash with Perth Glory at ANZ Stadium on Sunday.

The Brazilian has not trained all week as he attempts to shrug off a thigh injury sustained in the club's 1-0 derby win over Western Sydney Wanderers last Saturday night.

Youngster Daniel Petkovski trained in the left-back position on Friday and is the likely replacement should Fabio fail to recover in time.

But given Sydney's injury woes in defence already this season - with Pascal Bosschaart and Adam Griffiths already unavailable - coach Ian Crook is desperate to avoid another change to his back four.

"We're going to give Fabio as long as we possibly can," Crook told reporters on Friday.

"He wasn't able to train today but we'll see how he is (on Saturday) and make a decision then.

"(Petkovski) did well when he came on (against Wanderers) but we've got a couple of options that we can maybe look at there.

"Obviously if Fab's no good then Daniel is in the box seat at the moment."

Asked how disruptive the constant changes to his defence have been, Crook said: "I don't think we've put the same team on the park for the three games already.

"We were hoping to do that this weekend. And we'll see, we might still have that opportunity with Fab.

"It's frustrating but then we've got to trust the people that come in to do a good job for us."

The Glory have injury issues of their own with star striker Shane Smeltz again misssing out due to a hamstring injury.

But Crook knows Ian Ferguson's side are about more than just the goals of the New Zealand international.

"We're talking about grand finalists last year, and they were probably unlucky not to win the grand final," the Sydney coach said.

"(Stephen) McGarry's done a really good job for them and (Billy) Mehmet came in last week and scored and he gives them a presence up there.

"I think he's (Mehmet) a far better player than what people give him credit for.

"It's going to be a real tough one for us on the weekend.

"You can feel the difference in everybody with the win. It was good to get it but important for us to carry that on (this) week."

Sydney are enjoying an eight-game unbeaten run against the Glory, with their last loss to the Perth club coming way back in November 2009.