Corica ruled out

Sydney FC has been dealt a major blow ahead of Sunday's clash against Perth Glory, with skipper Steve Corica ruled out after failing to recover from a hamstring strain.

Sydney FC has been dealt a major blow ahead of Sunday's clash against Perth Glory, with skipper Steve Corica ruled out after failing to recover from a hamstring strain.

Corica suffered a grade-one strain in the early stages of his side's 1-0 loss to Gold Coast United a fortnight ago.

While the 36-year-old has made steady progress, coach Vitezslav Lavicka is not prepared to take any chances with the in-form veteran.

"Steve Corica's hammy looks much better than last week and the week before but still it's not 100 percent ready to play in Perth this week," Lavicka said on Thursday.

"We have a couple of other opportunities how to replace him and we'll decide (who will take his place) tomorrow."

Lavicka may decide to start Brendan Gan who replaced Corica in the Gold Coast clash, while his other option is to start marquee man John Aloisi up front and shift the in-form Alex Brosque to the left wing.

Defender Simon Colosimo, who is making his first trip back to Perth since parting company with the Glory at the end of the 2007/08 season, concedes Corica will be sorely missed but believes the Sky Blues have the depth to cover his loss.

"It's massive, I mean look at our front half of the pitch it's been great we've found some touch and found some form," Colosimo said.

"But we've had that all season where important players have gone down for an extended period - Terry McFlynn, John (Aloisi), Stevie (Corica), Stephan Keller ... but it creates opportunities for other boys."

Finding a replacement for Corica is not Lavicka's only selection dilemma with central defender Keller now fully recovered from the knee injury which saw him miss a month of action.

Keller was forced to come off the bench in his return match against Gold Coast behind regular right-back Sebastian Ryall who performed well in his absence.

"In this moment it's hard to say, I cannot say now but we have now one more option for our defence line," a coy Lavicka said when asked if the Swiss would reclaim his starting spot.

Colosimo insists he is unsure which way the coach will go admitting both players are evenly matched.

"It's touch and go, Stephan was great for those few games and then he got injured and Sebastian stepped in. I mean he's got a Championship (with Melbourne Victory) under his belt and he's played alongside Kevin Muscat so I'm sure he knows how to play in the big games," Colosimo said.

The Sky Blues enter the clash desperate to maintain top spot on the A-League ladder, while Perth, currently in fifth spot, will be desperate to claim maximum points at home.