Collingwood star Steele Sidebottom faces likely suspension for multiple breaches of the AFL's strict coronavirus protocols.
The All-Australian midfielder and teammate Lynden Dunn shared an Uber ride on Saturday evening and Sidebottom later visited a member of the club's staff who is not living under the competition's protocols.
Both players have been interviewed by the AFL's integrity unit, which is expected to complete its investigation on Wednesday.
"The breaches were reported to the AFL on Sunday afternoon," the Magpies said in a statement released on Tuesday evening.
"The players were interviewed by the AFL yesterday (Monday).
"Sidebottom and Dunn will not be permitted to return to the Holden Centre until cleared to do so by COVID-19 testing."
If Sidebottom is banned, it would be a massive blow for Collingwood ahead of their clash with Essendon at the MCG on Friday night.
The 29-year-old Magpies vice-captain has played in each of the club's four games this season.
Dunn, 33, has struggled with injuries and has not played at senior level since 2018.
The pair reportedly spent part of Saturday night drinking with teammate Jeremy Howe, who sustained a serious knee injury during the previous night's loss to Greater Western Sydney.
Sidebottom then reportedly visited former teammate Daniel Wells, who works for Collingwood but is not part of the club's approved list of 25 staff members.
Sidebottom's three alleged breaches are spending more than two hours with Howe, catching an Uber ride and visiting Wells.
Dunn's only alleged breach is the Uber ride.
The latest transgressions follow suspensions being handed to five players for breaches since the AFL return-to-play protocols were implemented.
Essendon's Conor McKenna and Brandon Zerk-Thatcher, Melbourne's Charlie Spargo and Kysaiah Pickett, and Port Adelaide's Ollie Wines have all been suspended for breaches.