The Sky Blues were already set to be without suspended Nick Carle and Hagi Gligor, who is with the Australian Under 22 team at the Asian championships in Oman, before Farina revealed on Thursday that Garcia will also miss Sydney's trip across town due to a calf injury.
Farina has not picked the same starting line-up in seven straight games with injuries and suspension having been a key factor in Sydney's inconsistent season so far.
"Last week against Adelaide, he (Garcia) finished the second half but halfway through he was complaining about pins and needles just behind his calf and it looks as though that might have been a little bit of a strain," Farina said.
"He managed to finish the game but there's quite a lot of bruising there now, so it is a bit of a strain and there's no way he'd be right for this weekend."
Sydney have won six games and lost six so far and will take on their cross-town rivals knowing a loss would see them slip seven points behind the Wanderers.
While Farina has plenty of experience to call on in central midfield to replace Carle and Gligor - including Brett Emerton, Terry McFlynn and Matt Thompson - the 49-year-old coach is frustrated at being forced into changing his starting XI again.
"We have options in there (defensive midfield) but it's still not nice when you lose three or four players from the previous week - one through suspension, one through national team duty - but again, I think we've got the depth that we can cover that," Farina said.
Despite Sydney's holes in midfield this week, Farina ruled out picking Serbian midfielder Milos Dimitrijevic.
The 29-year-old former Red Star Belgrade and Nantes player, who is set to sign with the Sky Blues after they released Panamanian forward Yairo Yau on Wednesday, has not played a competitive game in over a year.
But Farina said Dimitrijevic will be ready to go soon after he only arrived in Sydney on Sunday.
"He's in pretty good nick, when you look at him," he said.
"It was similar with Ranko (Despotovic), when he came in, and we saw how quickly he adapted and was physically up to it.
"So I'm not expecting it'll be too long before we see him (Dimitrijevic - on the pitch)."
