Thomas has been made to watch his side remain winless from the sidelines after sustaining an ankle injury in a training accident one month out from the new season.
The club's No.1 goalkeeper tripped over a stray ball during a drill and underwent keyhole surgery to clean out further cartilage damage.
Originally eyeing a return in round three to bolster their defence against the Reds, Western Sydney coach Alen Stajcic now admits Thomas's chances are slim.
Wanderers coach Alen Stajcic watches on during his side's 1-1 draw at Western United. (James Ross/AAP PHOTOS)
Emerging star Tristan Vidackovic has stood in, with back-up goalkeeper Jordan Holmes also unavailable through injury.
"(Thomas) is possible, but I still say he's maybe another week or two away," Stajcic said on Wednesday.
"We wouldn't rule him out just yet. He's certainly training a lot better and a lot more comfortable.
"We'll make a decision on that later on in the week."
New signing Jeong Tae-Wook has been handed the mammoth task of replacing former captain Marcelo but has yet to gel alongside fellow centre-back Alex Bonetig.
A disjointed backline and an error from Jack Clisby opened the door for Western United to deny the Wanderers their first three points last time out.
Ahead at halftime courtesy of a Brandon Borrello goal, Hiroshi Ibusuki volleyed home in the 48th minute when Clisby failed to fully clear the ball with his header.
First goal in Green and Black for our new No.9 🤩— Western United FC (@wufcofficial) What a hit from Hiroshi 💚🖤#WUNvWSW pic.twitter.com/hzlAJdUyXTOctober 27, 2024
But Stajcic remains level-headed.
"We haven't conceded 50 goals. We've conceded three in two games," Stajcic said.
"'Wookie' actually had a good game on the weekend.
"He probably had one or two moments where he could have done a bit better but considering the amount of pressure he was under, I thought he thought he did a good job.
"And you know, Bonetig is growing all the time as well. He's only played 30 or 40 A-League games but he's got a bright future ahead of him.
"I don't think it's incumbent upon just those two or a backline to be leaders. I think that needs to happen across the pitch."
Western Sydney will return home to CommBank Stadium to host Adelaide, who are also looking to clinch their first win.
