The 37-year-old, who has scored a record 50 goals in 103 matches for his country, said he and two personal physiotherapists had been working around the clock on the ankle since he injured it in an A-League match on Friday.
"I'm definitely not going to promise anything ... but this is a massive occasion for us, the chance to make it to a fourth consecutive World Cup, so we're making a calculated decision," he told reporters at Melbourne airport.
"If it works, fantastic. If it doesn't then, I'll be accountable.
"It's a massive two weeks for Australian soccer and I understand all the stuff around me travelling but I wouldn't be doing it if I thought it was the wrong thing."
Cahill, whose brace in Sydney proved decisive in getting Australia past Syria in the Asian World Cup playoff, said the treatment on the damaged joint would continue throughout the long flight to Central America.
The rest of the squad were already on their way to San Pedro Sula from their various clubs around the world.
Team officials said on Sunday that VfL Bochum forward Robbie Kruse had been ruled out of the match and would rejoin the squad with suspended midfielder Mark Milligan and striker Mathew Leckie for the second leg in Sydney on Nov. 15.
Barring a sending off, Australia will not lose any more players to suspension for the second leg after FIFA agreed to cancel any outstanding yellow cards that had not already resulted in bans.
Football Federation Australia (FFA) welcomed the move, which was made after considering the higher number of qualifying matches the Socceroos had played compared to Honduras.
"This decision is a victory for Fair Play," said FFA chief David Gallop.
"We thank FIFA for considering this exceptional circumstance and making their decision (which) will allow both teams to field their best players, on even terms, for these extremely important playoff matches, which is what all football fans want to see."
Victory over the two legs would secure Australia a place at the finals for a fifth time.
(Reporting by Nick Mulvenney in Sydney,; Editing by Andrew Both/Peter Rutherford)
