'Pies lose AFL backman for up to a month

Collingwood have suffered another setback, losing defender Marley Williams for up to a month.

The 22-year-old suffered a mid-foot sprain in a collision during Saturday's upset 29-point AFL loss to St Kilda.

Williams played 20 senior games last season for a career total of 60.

Coach Nathan Buckley says Williams' foot will be in a moon boot for about a fortnight.

"We've played 12 defenders in the first three weeks so we're looking for a little bit of continuity," Buckley told Fox Footy's AFL360 program on Monday.

The Magpies are misfiring with a 1-2 start to the season.

Last week, Buckley was unhappy with Collingwood's contested ball work and now defence has emerged as an issue.

"Our issue was just defending - we have to defend better," he said of the St Kilda loss.

"It's been highlighted that I had a crack at our forwards and we need to pressure better at the front end but there's plenty we can do through the middle and down back to be able to stop the opposition."

In the past two games, the opposition have taken 19 marks in their inside 50.

"They're big numbers - the averages are nine or 10," Buckley said.

He added that Collingwood think they have worked out the problem, saying it is a combination of attitude and tactics.

After a promising pre-season, the Magpies look badly out of sorts at the start of a season where they are expected to make a top-eight return.

"We need to be a side that defends better ... that holds the ball better in our front half and clearly supports our back six a little bit more," Buckley said.

"Right now, the feedback we're getting from the way the opposition are moving the ball is that we're not getting it done.

"It's a coaching issue as much as a playing issue."