ADELAIDE young gun Patrick Dangerfield has been ruled out of his club's all-important game against Collingwood on Saturday night due to a back injury.

Dangerfield, who is one of just eight Crows to play every game this season, failed to join his teammates at Wednesday’s main training session.

All-Australian centre half-back Nathan Bock also sat out the session.

The moon boot protecting Bock’s bruised heel will be removed in the coming days and the club still expects him to play against the Pies.

Midfielder David Mackay (hamstring) trained strongly and will be available for selection.

Adelaide defender Graham Johncock missed the round one win over Collingwood after the sudden passing of his mother, but said his side would be out to produce a similar performance at AAMI Stadium this week.

“The guys played really well that day [round one]. I was back home watching in Port Lincoln at the time, but everybody played their role,” Johncock said on Wednesday.

“A lot of the younger guys played well. The weight of numbers took its toll that day and the boys were able to get over the line. We’re expecting the same sort of stuff this week.”

Johncock, 26, has been in solid form since returning to the side in round two and his past five weeks have been particularly impressive.

Johncock has averaged 28 possessions a game during this period and provided plenty of run and carry from defence.

The creative back pocket said it was satisfying to be playing some good football after a tough start to the year.

“The passing of my mum was a bit of a shock and I found it pretty difficult, but the club, all the people involved and the players were very supportive. Their support has definitely made it a lot easier for me to come back and play footy,” he said.

“Mum was a pretty big footy fanatic, so she’d be pretty happy right now. It would’ve been pretty easy for me to say stuff it and to go back home among family and friends, but it’s not what she would’ve wanted.”

Johncock is likely to have a big job on one of the in-form Collingwood small forwards this week.

He said stopping the likes of Alan Didak and Leon Davis would go a long way towards winning the game and securing the club’s fifth successive finals berth.

“Alan Didak, Leon Davis, Dale Thomas and Paul Medhurst are all very dangerous, so there are going to be some pretty big match-ups for some guys. Hopefully, we can do the job.”