Mantha (lower body) wasn't at practice and will miss Thursday's game in Boston, Pat Steinberg of Sportsnet 960 The Fan reports.
Mantha was injured in the opening stanza Tuesday and did not return. Head coach Ryan Huska said Thursday that Mantha was "still being evaluated." Mantha has four goals and seven points in 13 games this season. Look for Kevin Rooney to enter the lineup in Mantha's absence.