Cahill, at 37, remains an indispensable member of the Socceroos. His two headed goals earned Australia a 2-1 victory over Syria.
The country's all-time leading scorer remained on the bench during the goalless first leg in San Pedro Sula on Friday but said he was expecting to make an appearance in Wednesday's do-or-die match to qualify for Russia 2018.
And the 103-cap forward said he would be ready to start if called upon by coach Ange Postecoglou.
"If I had to play in Honduras I definitely would have made a contribution," Cahill told reporters.
"That's what it's all about, putting your body on the line and sacrificing for these two games, for such a big occasion for our country to qualify for a fourth consecutive World Cup."
"I'm feeling really good. It was awesome to train in Honduras and get two sessions in so I feel great. I feel like I'm going to be involved and it's all about Wednesday night."
Cahill, at 37, remains an indispensable member of the Socceroos. His two headed goals earned Australia a 2-1 victory over Syria in Sydney last month to set up the intercontinental playoff with Honduras.
"We always respect our opponent but from the performance we've seen in Honduras, I feel the team is ready to put in a good performance," he said.
Attacker Mathew Leckie, who did not make the long trip to Honduras because of a hamstring injury, has also declared his availability for the Sydney return leg.
"I feel really good. I was pretty good before leaving my (Hertha Berlin) club. I probably could've made the squad for (last) weekend but we just decided there was no point risking it," Leckie said.
"Bit of a setback because I haven't been able to play, but it's two weeks. I don't think I've lost too much fitness. I'll be good to go.
"Our goal is to dominate the game on Wednesday and I think we can do that."
Leckie said he expected the pace of the Sydney game to be quicker than the heavy pitch conditions experienced in Honduras.
"We controlled the game over there in very poor conditions. The pitch looked very tough and the guys did very well," he said.
"The away goal would've been nice, but with us getting back early, we’ve got all the right people to get us right, the pitch is going to be in good condition so we can move the ball.
"The speed of the game will be much faster and I think we've got a better team."
The Honduras squad touched down in Sydney early on Monday less than 60 hours before the second leg kicks off.
The central Americans arrived a day after the Socceroos touched down in a special chartered plane, equipped with player treatment tables.
After an afternoon recovery session, the Honduras team will have only one full training session before Wednesday's showdown at the Sydney Olympic stadium.