Thomas is racing the clock to prove his fitness after injuring his ankle in a "freak" training accident one month out from the A-League Men 2024/25 season.
After injuring the two outside ligaments in his ankle after tripping over a stray ball during a training drill, the Wanderers skipper underwent keyhole surgery to clean out further cartilage damage.
Little more than a fortnight away from the Sydney derby, Thomas remains realistic about his chances of playing in week one.
Western Sydney will host fierce rivals Sydney FC on October 19 in round one, with the two teams to unveil their respective marquee signings Juan Mata and Douglas Costa.
"Playing in round one is quite slim," Thomas told AAP of his chances.
"I'm not going to say mentally I've ruled myself out but with the advice of the professionals, I'm probably looking at round three.
"I'm fighting to get back as quick as I can."
Juan Mata will be unveiled as the Wanderers' marquee player against Sydney FC on October 19. (Steven Markham/AAP PHOTOS)
The Wanderers will begin their first campaign under coach Alen Stajcic after battling through a turbulent season with Marko Rudan.
Their form nosedived in the back end of the 2023/24 season and they missed the top six in the final round of the campaign.
Thomas's absence due to international duty and injuries to star striker Brandon Borrello also hampered the Wanderers' campaign.
Rudan, who served a two-match suspension for his verbal attack on referee Adam Kersey, stepped away from his post for personal reasons despite signing a three-year contract extension.
Stajcic then joined the club on a one-season deal after leaving Perth Glory with two years left on his contract.
Named captain by his peers after Brazilian defender Marcelo's departure in the off-season, Thomas says the club are determined to return to the top of the ladder.
The Wanderers have already hit their first speed bump, bowing out of the Australia Cup with a 2-1 quarter-final loss to Adelaide United.
"(Missing finals) certainly burned last year," Thomas said.
"For the team we had, the squad we had, at a bare minimum, we should have made the finals.
"This year, we're full of excitement. We all fire for each other and I expect us to be a lot higher this year.
"The people in this area deserve more on the field. It's been a while for them to have a team that's dominating and on top of the game in this country.
"That's a big goal for us this year."
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