Jobe Watson's absence over the next four to six weeks will test Essendon.
That's no surprise – the last time the Bombers played without Watson was almost two years ago, when it was his hamstring rather than his collarbone which kept him out of action.
Watson missed six games with two separate strains of the muscle in 2011, and the Bombers won three of those games, including a thriller over Geelong when few thought they were a chance. But before that, the Bombers had lost their previous seven games without their No.4, dating back to 2007.
For so long, Essendon's midfield has been centred around Watson: his quick hands, his bullocking work, his capacity to bring others into the game. Now, more than ever, they are in a better position to cope without him.
Brendon Goddard seems likely to move into a more 'inside' role. Questions hung over his ability to play as that ball-winning midfielder before he crossed to Essendon, but he has consistently done that this year, averaging nine contested possessions a game and three clearances.
He will fill the breach in a leadership fashion, as will David Zaharakis, who is steadily growing in that way, having learned bits and pieces from Watson's captaincy.
More responsibility might also be thrust towards David Myers. Myers is enjoying his best year of football since joining the club, having played every game following his first injury-free pre-season at Essendon. He was prepared for this sort of year, and this sort of opportunity.
Although used sometimes off half-back or on the wing, Myers trains as a midfielder, and has the traits to fill Watson's role, at least temporarily: he is an extractor, at home at the clearances, with a big body. In stature terms at least, Myers is almost an identical replacement for his captain.
This week presents its own challenge. Watson is out, Heath Hocking's calf injury is lingering, and Brent Stanton is in some doubt with an ankle injury. James Hird might be without three of his best midfielders.
Essendon's healthy list, aside from the trio, means it has options. Nathan Lovett-Murray had a solid day in the VFL last week and could be brought in to add some strength around the ball, while Elliott Kavanagh is due for another run.
Leroy Jetta has been excellent in the VFL, but has yet to take his chance as a midfielder at the top level.
None compare to Watson, of course, who was a leading favourite for back-to-back Brownlow medals before the injury.
But the cumulative output of the other midfielders like Ben Howlett, the improving Jake Melksham and the consistent Dyson Heppell, as seen against Port Adelaide on Sunday, could make the loss of Watson a manageable problem rather than a debilitating one.