De Goey will undergo surgery on a broken hand this week after sustaining the injury in an accident at home over the weekend.
The young Pie will now be unavailable for selection for two to three weeks.
Greenwood will spend a little more time on the sidelines than De Goey, as upcoming hip surgery is set to keep the midfielder out of action for the next four to five weeks.
“It’s disappointing to have to rule out players leading into the season opener, however it opens the door for other players who have had strong pre-seasons to get a crack at the reigning premiers this Friday night,” said Collingwood general manager of football Geoff Walsh.
The injury news comes just days after the Pies confirmed Jamie Elliott would also miss the clash with the reigning premiers after failing to overcome an ankle injury.