Collingwood coach Nathan Buckley has put his forward line on notice after a 40-point loss to North Melbourne.
Buckley cut a despondent figure on Friday night, having earlier in the week likened the match to a final for his AFL club.
Buckley was unhappy with the lack of "effort" showed by his entire side as North strolled to a 27-point lead at quarter-time.
But he saved his most stinging criticism for the Magpies' forwards.
"We were impotent forward of the ball for most of the first half and we thought we went in with probably one of our better forward lines, on paper, for the year," Buckley said.
"North Melbourne's pressure on the ball was able to prevent any clean ball coming forward but at the same time our forwards just didn't work hard enough."
Buckley was unwilling to single out spearhead Travis Cloke, who finished with eight touches and three marks.
"He's part of the forward line that really struggled. All the forwards are probably on notice," Buckley said, when asked if Cloke would be dropped.
Buckley also wouldn't be drawn on whether wholesale changes were needed but failed to hide how unhappy he was with some players.
"If we're not getting bang for buck or we're not playing the way we want to play, often enough, then we keep shuffling it around," he said.
"We pick our best side every week. Individuals had a chance tonight to reinforce (if they are in it).
"Some did, some didn't.
"We want to find out who can stand up ... we're getting some pretty good feedback."
The Magpies are likely to make at least one forced change, with Ben Sinclair taken to hospital after being knocked out at Etihad Stadium.
"It is (a concern). He's an important player for us," Buckley said after Sinclair's third concussion of the season.
"His health is the most important thing ... he'll take a little bit of time to get right."