Last week's 3-2 home win over Saudi Arabia put Australia back in the driving seat to reach the 2018 World Cup in Russia, where Cahill has his heart set on making a fourth appearance at the global tournament for the Asian champions.
"My end goal is to get to Russia, but when 23 players are selected it starts from 20 to 60 players who have been a part of this long campaign for two and a half years with the boss," Cahill told reporters.
"When we leave this camp we're always knowing it could be your last ever camp, regardless of whether you're 21 or 37... it comes down to the football, that's the main element we get judged by.
"It's nice to be kept on your toes... it's great to be here, but Russia 2018 is still too far ahead. The big game for me is (against Brazil) and then after that the Confederations Cup."
Cahill was an unused substitute against Saudi Arabia in Adelaide on Thursday but is very much in Postecoglou's plans for the Brazil match as the coach seeks to give all of his squad a chance to impress.
"Timmy is one of the ones who will get some game time for sure," Postecoglou said of the Melbourne City attacking midfielder.
"Obviously the A-League finished a while back, but to be fair to him he's worked really hard in the meantime."
Coming off the bench is also something that does not concern Cahill, with the player admitting he is always fully prepared whether selected as a starter or a substitute.
"You've got in the back of your mind the certain levels you need to be at professionally, and the best thing about coming into camp is being on level pegging with every single player, regardless of age," Cahill said.
"The fitness has to be high, your data has to be good and everyone is in for a selection opportunity."
(Writing by John O'Brien in Singapore; Editing by Sudipto Ganguly)
