Sabres interim coach Ron Rolston told the media after the team's morning skate that Vanek is still sore from being hit with a shot in the second period on Tuesday in Montreal.
Vanek was in front of the net on a Buffalo power play when he was struck by defenseman Christian Ehrhoff's shot from the point. The Sabres are calling it a lower-body injury. Vanek did not take the ice Thursday.
"He's better today," Rolston said. "He feels, actually, good and starting the process, so we're hoping to get him on the ice tomorrow."
Vanek could return for Buffalo's road game against the Montreal Canadiens on Saturday. He leads the Sabres in scoring with 14 goals and 17 assists in 27 games.
John Scott, a healthy scratch the last three games, could be back in the lineup for Buffalo against Toronto. Nathan Gerbe is also a possibility, but he was a healthy scratch Tuesday and took extra time on the ice after practice Thursday.
"We can only have 12 forwards in there and [Gerbe] was a player that I think didn't give us a reason to keep him in right now. And that's what he has to work for," Rolston said.
Lupul received a minor penalty for an illegal check to the head after hitting Lightning defenseman Victor Hedman early in the third period. He has a hearing with the Department of Player Safety at 2 p.m.
Here are the projected lineups for both teams:
Scratched: Nathan Gerbe