Australia will have just 13 fit players to choose from for their clash with Pakistan after Ashton Agar registered their second positive COVID result in as many days.
Less than 24 hours after Josh Inglis entered isolation with the virus, there are fears of an outbreak with both Agar and a team staff member also contracting it.
The news leaves Australia with a severely reduced squad just hours out from the first ODI against the hosts, after Mitch Marsh was also struck down by a hip injury in training.
"Australian spinner Ashton Agar tested positive to COVID this morning, making him unavailable for the one-day international series against Pakistan in Lahore," Cricket Australia said in a statement.
"Team physiotherapist Brendan Wilson also tested positive this morning. All other players and staff returned negative tests."
Australia have flown Matt Renshaw over to help boost numbers, but he must serve three days in isolation before joining the squad.
It means any further cases would leave the rest of the tour in doubt, with ODIs to come on Thursday and Saturday before a Twenty20 on April 6.
Australia had previously avoided any serious contact with the virus during the Test series, with Pakistan's camp being the only one impacted.
Pakistan recorded just 186 new cases across the country on Monday according to official data, with 310 reported on Sunday.