Andrei Markov will not be back for Monday night's game, Montreal coach Jacques Martin added. The Penguins lead the Eastern Conference semifinal 3-2.
Gill left during Montreal's 2-1 loss in Pittsburgh on Saturday night after he was cut on the back of his left leg by the skate of former teammate Chris Kunitz. He remained in Pittsburgh overnight for treatment.
"They wanted to make sure everything was all right so they took their time with it," said Gill, who returned to Montreal with Canadiens team physician Dr. David Mulder on a commercial flight Sunday.
The 6-foot-7 defenseman skated briefly after his teammates practiced at Bell Centre.
"I just wanted to get my feet under me and skate a little bit," Gill said.
Martin said he'll wait until after the pregame warmup to decide if Gill will play. Spacek also will be a game-time decision after missing nine straight games because of an undisclosed virus.
Markov skated for a second straight day after hurting his right knee in the series opener.
"His condition is indefinite," Martin said. "He's ruled out for tonight."