Injury doubt Josh Kennedy is being monitored by the Socceroos staff ahead of the cut to a final World Cup squad of 23, with Ben Halloran admitting the nerves are mounting among the players.
Kennedy was withdrawn at short notice, apprently as a precaution, before Australia's 2-0 friendly win over local side Parana Clube on Monday.
The veteran striker came off the bench in the 1-1 farewell game against South Africa in Sydney last month, but assistant coach Aurelio Vidmar confirmed the fitness of the Nagoya Grampus centre-forward is a concern for Ange Postecoglou.
"That's a discussion we'll have with the coaching staff and the medical staff as well, to see where he's at," Vidmar said.
"And we'll look at that closely, as we will everyone else in the squad."
Another player potentially in line for the chop is Swindon Town's Massimo Luongo, who is highly rated but also the most inexperienced member of a well-stocked Socceroo midfield.
Fortuna Dusseldorf forward Ben Halloran has been impressed by the former Tottenham Hotspur player, as the squad faces a nervous wait to discover which four players Postecoglou will deem surplus to requirements.
"Mass is very good in the midfield, he plays a lot of intricate passes in the midfield, so playing with (him) made my job a lot easier," he said.
"To say there's no nerves would be pretty ridiculously but there's a lot of stiff competition, so it's going to be a pretty restless night."
The biggest question mark appears to be hanging over Tom Rogic, who was withdrawn at half-time in the game against Parana Clube after appearing to be in some discomfort.
The 21-year-old could well be deemed not fit enough to justify taking up one of the 23 places in the World Cup squad, although Vidmar offered a reminder of why the Celtic man has been allowed every chance to prove himself to Postecoglou.
"He's certainly for me a very special player," he said.
"He's young, he's got a lot to learn. But he's one of those types of players who can, in a second, turn a game for you."
Experienced defender Luke Wilkshire spoke up in support of Rogic, claiming the recent Melbourne Victory loanee appears to be making progress in his rehabilitation from a nagging groin problem.
"Look I've been speaking to Tommy quite a bit in camp," he said.
"I think he's getting there. Obviously he wants to be playing more and to be on the field more. But it's gradual and you can't force these sort of things. Hopefully he'll right in the coming days."