Should Rask be unable to start on Thursday night against Vancouver, Anton Khudobin is prepared to fill in between the pipes.
"You don't want to see that," Khudobin said of the collision. "I'm always ready. If I need to go tomorrow, I will."
Khudobin made 29 saves on 31 shots in Boston's 6-2 victory over Arizona on Saturday.
"We liked the way Anton played last year at the end of the year, we liked he's camp, we liked his first game," said Cassidy. "We sort of mapped out the schedule for October. We're gonna stick to that. Obviously if we have to deviate because of an injury then we'll do that and have confidence in him for sure."
Patrice Bergeron practiced in a red non-contact jersey, once again, but appeared to engage in more physical activity during Wednesday's session. As a result, Cassidy would not completely rule the center out for Thursday's game against Vancouver.
"Bergeron made it through practice, progressing well," said Cassidy. "In the past we've basically ruled him out ahead of time…we're not ruling him out tomorrow, I'm not saying he's in.
"How they approached it today, they were gonna let him play it out by feel today. He was gonna be non-contact but if he's feeling pretty good in practice they were gonna let him stay a little longer and that's how it worked out.
"Wasn't gonna be a heavy contact day…he seemed to progress well from it so he stayed out there."
Cassidy did say that David Backes and Adam McQuaid seem closer to being ready to play against the Canucks. McQuaid, who missed Tuesday's practice after leaving Sunday's game in Vegas with a lower-body injury, said he felt no ill effects upon his return to the ice on Wednesday.
"Didn't have much feeling in my leg at first, so once that came around obviously I felt a lot better today," said McQuaid, who took a puck to the knee in the closing minutes against the Golden Knights. "I felt good out there today, was able to do everything I needed to do…good to go. Really good treatment yesterday made a big difference. Happy with how quickly it turned around."
Ryan Spooner was the lone player to miss Wednesday's practice. The forward suffered a lower-body injury against Vegas, leaving his status for Thursday night in question.
"He's getting evaluated," said Cassidy. "He didn't practice today, so it never bodes well the next day. I'm not gonna lie to you about that."