He is in trouble for an incident in the third quarter of Saturday night's loss to Hawthorn, with an elbow catching Daniel Howe high.

Cox and fellow key forward Ben Reid had minimal impact for the Magpies, despite having enough chances.

Coach Nathan Buckley said Cox had a solid pre-season but acknowledged the big American must rebound quickly from his poor round-one outing.

"It is a real test of character now - of ours and of his - as to how he responds to that," Buckley said.

"He's had a bad night.

"HIs challenge is to make it a bad night and not a normal occurrence and I'm pretty confident he'll do some damage."

Collingwood could have been much closer but kicked a wasteful 2.7 in the last quarter.

Buckley said their night was summed up in the final term when Josh Smith's shot on goal looked like it might go through.

Tom Phillips tried to make sure of it but he fumbled the ball on the goal line and it was only a behind.

"We had the personnel to be able to get the result and the last quarter showed that," Buckley said.

"We couldn't have played more poorly in larger chunks or have less contributors - and yet still be in the game.

"It was just a comedy of errors."

Smith also suffered a hamstring injury, while Ben Crocker had a knock to his back.

Star onballer Daniel Wells is at least a couple of weeks away as he returns from injury.

This is the third-straight year Collingwood have lost in round one and once again, the spotlight on Buckley now shines a little brighter.

"We've dropped a game ... we're 0-1 and we come up against the Giants next week," he said.

"We think we can perform better, so that's our job."

One positive for Buckley was the performances of first-gamers Sam Murray and Jaidyn Stephenson.

"They should hold their heads high ... both of those boys had a real crack," he said.

But overall, Buckley said Collingwood failed to cope with Hawthorn's pressure and were not clean enough with their ball use.

"We played an okay structured game and that's why we were still in the contest but we just didn't execute our opportunities well enough," he said.

"We didn't have enough blokes who brought their strengths to the table."

Australian Associated Press