Carlton star Jacob Weitering will undergo surgery on his injured right shoulder in a move that will sideline him for the next six weeks of the AFL season.
Weitering injured the AC Joint in a collision with Collingwood's Jordan De Goey during the Blues' narrow four-point defeat on Sunday.
The 24-year-old key defender was substituted out of the match before quarter-time.
Weitering underwent scans and sought further specialist advice on Monday, with surgery deemed the best course of action.
"We had a good indication soon after Jacob experienced the injury that it was a significant one, which has now been confirmed," Carlton football boss Brad Lloyd said.
"The surgery will take place in the coming days so he can commence his rehab as soon as possible."
Weitering's setback increases Carlton's need to add defensive cover at Wednesday's mid-season draft.
Mitch McGovern is sidelined with a long-term hamstring injury and Oscar McDonald has been ruled out for the rest of the season with a back injury.
Fellow key defender Liam Jones left the club in November because of his COVID-19 vaccination stance.
Brodie Kemp and Caleb Marchbank are in line to step into the void left by Weitering when the Blues take on Essendon after the bye.
"Our defence and the team as a whole has shown some outstanding resolve so far this season," Lloyd said.
"The players have really bought into that mindset.
"So while losing Jacob for an extended period certainly isn't ideal, it provides another opportunity to showcase the resilience that has become a trademark of this group."
Carlton have been linked to former North Melbourne defender Sam Durdin, who is playing with SANFL club Glenelg and shapes as a possible mid-season draftee.