The goalie will not play in home games against the Buffalo Sabres on Saturday (1 p.m. ET; SN1, NESN, MSG-B, NHL.TV) or the New Jersey Devils on Sunday.
Forward Brad Marchand also will not play against the Sabres after entering NHL COVID-19 protocol Saturday.
Rask played one period before leaving a 4-3 overtime loss to the New York Islanders on Thursday. He had not played since March 7, when he grabbed his back at the end of a 1-0 win against the Devils. He missed six games.
"Tuukka was in this morning, he will be getting treatment. He will not play this weekend and then we'll go from there," Bruins coach Bruce Cassidy said Friday. "Again, until he's back on the ice, hopefully there's nothing] major there, but obviously something's going on where he had to leave the game again with a similar injury as the last time. We'll have to make sure we [get it] looked at and make the right call the next time and make sure he's -- I guess, not make the right call -- we assumed he was ready to play. That's why he was in. He said he was, medical staff, but obviously we have to keep a closer eye on it if it's something that's going to flare up."
The Bruins, who had been off the ice since March 18 because of NHL COVID-19 protocol, practiced with Rask on Wednesday. They did not have a morning skate Thursday because of a scheduling conflict with their practice facility.
Rask made six saves and did not allow a goal in the first period against the Islanders. He was replaced to start the second period by Jaroslav Halak, who allowed four goals on 18 shots.
Cassidy said before the game that the Bruins planned to use a rotation of Rask and Halak for the rest of the regular season, and that it's not a priority to use goalie
[Dan Vladar
, who made one start in Rask's absence. But given Rask's status, that could change, with the Bruins scheduled to play their remaining 28 regular-season games in 45 days.
"Obviously, Tuukka has missed some time. He needs to get some work," Cassidy said.
The Bruins were in protocol since returning home March 19, one day after a 4-1 win at the Buffalo Sabres, which caused two games to be postponed (at the Sabres last Saturday and home against the Islanders on Tuesday).
NHL.com staff writer Amalie Benjamin contributed to this report
