North Melbourne vice-captain Luke McDonald will miss at least the next 10 weeks of the AFL season after having surgery to repair a torn pectoral muscle.
McDonald was hurt during Saturday's loss to Adelaide - his first game of the season after recovering from a thigh injury.
The 26-year-old tore a pectoral muscle attempting to lay a tackle against the Crows.
"It's a really unlucky type of injury and it's really disappointing for us given we missed Luke at the start of the year," North Melbourne's general manager of football Brady Rawlings said.
"We've gone to the specialists and the recommendation is for surgery so Luke will undergo surgery tomorrow to repair the torn pec.
"At this stage we think a recovery period in rehab probably around 10-12 weeks."
Rawlings described the absence of reigning club champion McDonlad as a "huge loss" for the winless Kangaroos.
"He's vice-captain for a reason, he won our best-and-fairest last year for a reason ... he's such an important player," Rawlings said.
The news is better for Kangaroos stalwart Ben Cunnington has won a challenge to the AFL Tribunal and his one-match ban for rough conduct has been overturned.
The star Kangaroos midfielder is free to play against Geelong on Sunday after successfully downgrading his rough conduct charge at Tuesday night's tribunal hearing.
Cunnington challenged a one-match ban for a high bump which felled Adelaide's Rory Laird.
Cunnington's bump in the second quarter of Sunday's match was deemed as careless, high contact and of medium impact by the AFL's match review officer.
The veteran onballer, through his tribunal advocate Rob O'Neill, accepted the careless and high contact aspects but argued the force of impact was low, not medium.
The three-member tribunal panel agreed and the downgrading meant Cunnington's sanction was reduced from a one-game ban to a $2000 fine.
Adelaide's Laird was knocked to the ground by Cunnington's bump and taken from the field but wasn't injured.
"He (Laird) plays out the rest of the game, dominates, and gets nine coaches votes," Cunnington's advocate O'Neill told the hearing.
AFL advocate Andrew Woods said the main point of the case was the potential to cause injury.
"To only focus on whether or not there was an actual injury would be an error," Woods told the hearing.
"... it would indicate that players can essentially behave in that manner and it's only when someone gets hurt that a more serious offence will be found against them - that is not is what the laws or the regulations contemplate."
All other players charged from round-four incidents accepted their sanctions.
Western Bulldogs defender Caleb Daniel copped a one-match ban for a dangerous tackle on Brisbane's Tom Berry while Hawthorn key forward Mitchell Lewis also accepted a one-match suspension for striking Fremantle youngster Caleb Serong.
Rookie-listed Rhyan Mansell made an expensive debut for Richmond, being fined a total of $4000 for two separate rough conduct charges in his club's two-point loss to Port Adelaide.