Australia coach Ange Postecoglou ruled attacker Mathew Leckie out of World Cup qualifiers against Kyrgyzstan and Bangladesh.
Leckie has been battling a respiratory illness that has prevented him from flying out of Germany in time for Thursday's clash with Kyrgyzstan in Canberra.
"He's out for both," he said.
"He's picked up some sort of bug and infection which meant he was unable to fly.
"We had a deadline of yesterday and he was still unable to get on a plane so he was ruled out."
Ryan has completed just four training sessions since recovering from knee surgery, which sidelined him for more than two months, while Davidson has battled a calf injury since arriving in the nation's capital.
"The work that we've done over the last two years means I'm not nearly as stressed about injuries as I was previously," he said.
"The guys that are here are in good condition and in good form. Apart from Josh Risdon and James Meredith, all have had good experience at international level so I'm a lot more comfortable.
"To be honest our last performance [a 2-0 loss to Jordan] wasn't that great so I would have made changes anyway.
"I'm certainly not losing any sleep over the players that aren't here. I'm comfortable the XI we put out tomorrow will deal with the task at hand."
Asked how much petrol he had in the tank for Thursday, Jedinak said: "A full tank.
"I got through the game physically very well and pulled up pretty good so I'm very confident in all the work I've been doing that I'll be in a good state."
The visitors have their own issues, with coach Aleksandr Krestinin confirming dangerous wingers Mirlan Murzaev and Anton Zemlianukhin would both miss the clash through injury.
"Our team in the last match didn't really seem weaker than [Australia]," the coach said.
"The Australian team has lots of titles and achievements; no-one can take that away from them."
