Australia have summoned Mitch Marsh to England as World Cup cover for the injured Marcus Stoinis, but have yet to request a formal replacement.
All-rounder Stoinis picked up a side strain while bowling against India and has been ruled out of Wednesday's game against Pakistan at Taunton.
Marsh will now link up with the squad, but will not become a formal part of the 15 unless Cricket Australia formally requests to remove Stoinis.
"Marcus won't be available, especially for tomorrow, so we're going to have to juggle around especially that all-rounder spot," said Australia captain Aaron Finch.
"We've got Mitch Marsh flying over just as a bit of a precaution. He was meant to fly over with the Australia A side on Friday, he's just coming a couple of days early as a bit of a precaution, if Stoinis doesn't recover quick enough or doesn't respond to treatment well enough over the next few days."
Finch, whose side have won two and lost one of their games thus far, expressed uncertainty over Stoinis' prognosis and admitted his absence made team selection a trickier proposition.
"I'm not exactly sure on how many games he'll miss. That's why Mitch is flying over," he said.
"It's still being assessed. And over the next couple of days we'll have a clearer picture on what that looks like.
"We've got to find a few more overs now, whether we play the extra batter or extra bowler, we'll wait and see, and especially tomorrow with the conditions. That's something we've got to juggle with."
Finch admitted the recent poor weather in England was beginning to play on his mind, potentially altering in-game calculations as well as the state of the group stage table.
"I think it might play a huge part in the next few days. Next week it starts fine and looks good across the country for the remainder of the tournament.
"But it's important that you get early wins on the board because if they do play a part you don't want to be on the wrong end of a couple of washouts that might leave you just outside that top four.
"You can never bank on rain or anything like that. You always prepare for the full 50-overs and then you work on the spot."
Finch reiterated his thanks to Virat Kohli for urging the crowd at The Oval to clap Steve Smith rather than boo him. He also suggested any England fans who want to make life hard for the former captain and team-mate David Warner on their return from ball-tampering bans might have the opposite effect.
"It was all class, wasn't it? It was great to see such an influential player standing up for what he believes is right," he said of Kohli.
"Obviously Steve and Dave have been copping their fair share from the crowd. Regardless of whether they get booed or cheered, that doesn't faze them too much.
"So sometimes it's best just not to poke the bear, but we know it's going to happen."
