Cammalleri is set to miss between 10 days and two weeks with a deep cut on his right leg.
The injury could have been worse, but no muscle or tendon was cut when he seemed to make contact with teammate Yannick Weber's skate during a 5-1 win in Winnipeg on Sunday. He is to be re-examined by team doctors Saturday.
Spacek, who is believed to have suffered a rib injury when he was checked into the boards, will be out for up to three weeks with what the team is only calling an upper body injury, coach Jacques Martin said Tuesday.
The Canadiens also lost defenceman Chris Campoli to an injury in their season-opening game last week in Toronto.
The Habs expect to have centre Lars Eller back for their home opener Thursday night against the Calgary Flames. Eller is returning from off-season shoulder surgery.
"We'll work him back into the lineup gradually," said Martin. "We're glad to have him back and he can help us, but we're going to manage his ice time carefully at the start."