Krug sustained an upper-body injury late in a 3-2 shootout loss to the Philadelphia Flyers on Nov. 10. The 28-year-old defenseman, who will miss his third straight game, did not play in overtime.
Krug has 13 points (two goals, 11 assists) and 11 power-play points in 17 games after scoring 53 points (six goals, 47 assists) last season. He has topped 50 points in each of the past three seasons.
Bergeron, a 34-year-old center, had one assist in 16:48 in Boston's 4-2 win at the Toronto Maple Leafs on Friday.
"[Bergeron] has a lower body that we're going to be careful with," Bruins coach Bruce Cassidy said. "He finished the game [Friday] night. We don't want it to linger."
Cassidy declined to say whether the lower-body issue was the groin injury that has become a recurring issue for Bergeron and lingered into training camp this season.
"I'm not going to say it's new, old or somewhere in between," Cassidy said. "He finished the game [Friday] night in a little bit of discomfort. If it wasn't a back to back, we'd hope he'd play the next game. Because it's back to back, we just want to be careful. We don't want it to end up missing four or five games or something worse."
Bergeron was replaced in the lineup Saturday by center Paul Carey, who was recalled from Providence of the American Hockey League. David Krejci replaced Bergeron on the top line with Brad Marchand and David Pastrnak.
Cassidy said Bergeron, who has 19 points (eight goals, 11 assists) in 19 games this season, could return Tuesday at the New Jersey Devils.
NHL.com staff writer Amalie Benjamin contributed to this report.
