Collingwood premiership defender Oleg Markov has been ruled out of Sunday's game against North Melbourne at Marvel Stadium.
Markov hurt his back on Friday during the warm-up ahead of Friday's main training session and was given Saturday's captain's run to prove his fitness.
"Pre-training we do some hands work inside and he jarred his back, so he couldn't train," Collingwood coach Craig McRae said on Friday.
"He is going to be a race to the line, so it will be interesting to see if he gets up."
Markov has been replaced by key forward Reef McInnes in the side.
Forward Ash Johnson has been brought in as an emergency.
The Pies will also be celebrating the debut of dashing defender Tew Jiath on Sunday.