The AFL injury hits keep coming for Collingwood, with the bad news confirmed for Matthew Scharenberg and Jamie Elliott.
Jeremy Howe and Brody Mihocek hope to be available for Saturday night's away match against Sydney but Scharenberg will undergo his third knee reconstruction.
Elliott is also sidelined again after re-injuring his left hamstring in the VFL.
Scharenberg limped off in the third quarter of Saturday's loss to Richmond after an innocuous incident.
He ruptured the anterior cruciate ligament in his left knee.
Scharenberg has had a brutal run of injuries, suffering foot problems before his knee reconstructions in 2014 and '15.
It will be the second time he has needed his left ACL reconstructed.
Coach Nathan Buckley said after the Richmond game that the whole club felt for Scharenberg, who was shattered by his latest setback.
Elliott was playing his second game in the VFL after resuming from his hamstring injury when he was hurt late in the last quarter.
Collingwood's leading goalkicker in 2015 and last season has not played any AFL games this year because of injuries.
The Magpies have had a torrid run of injuries, especially in the past few weeks.
Howe (concussion) and Mihoceck (ankle) were also hurt against the Tigers, but they are upbeat about being available for Saturday's SCG clash.
Howe was hurt when he was pushed into teammate Darcy Moore at a marking contest.
"It wasn't ideal to get a head knock early in the game, but in terms of the way I've pulled up I haven't had a headache or anything," Howe said.
"I've got a nice little lump on the top of my head, thanks to 'Darce'.
"But no scans on the head - I've pretty much done all the precautionary things as expected so I've just got to see how the week plays out."