Bruins' Hall week-to-week with upper-body injury
Montgomery added that Hall's injury is a bit more "significant" than the team initially expected.
Hall left Saturday's preseason clash against the Philadelphia Flyers late in the second period and didn't return.
The team initially tapped Zacha to fill in for the injured Brad Marchand alongside Patrice Bergeron and Jake DeBrusk to start the new campaign, but the Bruins will now audition A. J. Greer, Nick Foligno, and Trent Frederic in that spot, according to The Athletic's Fluto Shinzawa.
Bruins rookie Fabian Lysell also had to exit Saturday's contest after getting crunched along the boards by Flyers defenseman Rasmus Ristolainen, but the team considers him day-to-day, and he could play on Wednesday against the New York Rangers.
Hall, 30, ranked fourth on the team with 61 points in 81 games last season.
The Alberta native has 28 goals and 47 assists in 97 games as a Bruin. The Buffalo Sabres traded him to Beantown ahead of the 2021 trade deadline.
The Bruins' 2022-23 season begins on Oct. 12 against the Washington Capitals.