Tuukka Rask made his return on Thursday night, but only played 20 minutes before exiting after the first period with an upper-body injury. The netminder did not skate on Friday and will not play this weekend, according to Cassidy. Jaroslav Halak will likely make the start on Saturday.
"Tuukka was in this morning. He'll be getting treatment," said Cassidy. "He will not play this weekend and then we'll go from there…don't believe there's anything major there but obviously something's going on where he had to leave the game again with a similar injury as the last time.
"Have to make sure we get it looked at and make the right call the next time…we assumed he was ready to play, that's why he was in. He said he was, medical staff, but obviously have to keep a closer eye on it it's something that's going to flare up."
Karson Kuhlman also missed practice on Friday to undergo an MRI after blocking a shot with his left hand on Thursday night. The winger has been ruled out for Saturday's matinee.
"Obviously blocked the shot - I think everyone saw that part of it - and couldn't hold his stick today," said Cassidy. "He's going to get looked at to make sure there's nothing. I think when you talk about those smaller bones you've gotta take a closer look.
"Depending on the MRI, if it's negative or no damage, then it becomes a matter of comfort with holding a stick. I'd only be speculating when that could be, but he'll be ruled out for [Saturday]."
Zach Senyshyn practiced in full on Friday and is expected to take Kuhlman's place as the third-line right wing alongside Charlie Coyle and Anders Bjork. Senyshyn has not played since suffering an upper-body injury in his season debut on March 11.
"Does feel like he's going to be able to play, so assuming there's no tenderness in the morning or something that would prevent him that crops up then he'll go in Kuhlman's spot," said Cassidy.
Jeremy Lauzon is "very, very close" to a return from the fractured hand he suffered during Boston's win over the Flyers at Lake Tahoe on Feb. 16. The blue liner skated with the group on Friday but remains day-to-day and will not suit up against the Sabres.
"He just needs reps, I guess, right now with his hand, make sure he handles pucks, comfortable with handling pucks," Cassidy explained. "Tough to get him in regular practices now because we just don't have that many. We had one today, obviously play tomorrow and Sunday… it's a little tougher for him to find what he needs right now with the frequency of our games and our schedule."
Boston's other injured blue liners, Brandon Carlo (upper body) and Kevan Miller (knee), skated before practice with winger Ondrej Kase (upper body) as they continue to progress toward a return to game action.
"No," Cassidy said when asked if Carlo's absence was the result of a setback. "We had eight defensemen and today was a day that Lauzy needed to get his reps in and [Jack] Achan is our seventh right now. We felt with nine that would be a lot, so Brandon got in [a practice on Wednesday]. He was on, feeling better, able to participate but we paired the group down."
