''It was pretty bad,'' Buffalo coach Ted Nolan said after Boston's 4-1 win. ''According to the medical staff, it wasn't too good.''
Nolan said Hackett's leg wasn't broken. He added that the goalie would return with the team to Buffalo where he would be examined by club medical personnel.
Krug was skating toward the net when he was upended by Buffalo defenseman Jamie McBain and fell on Hackett's leg in the crease with 11:35 left in the third period.
''I just felt like my feet got kicked out from under me, and I landed on his leg,'' Krug said. ''For a second I thought he was OK and then he started screaming. So I feel bad.''
Hackett remained sprawled on the ice, face down. After more than five minutes, he was carefully placed on a wheeled stretcher.
Hackett, who had been recalled from Rochester of the AHL on March 17, was replaced by Connor Knapp with Boston leading 3-1. Knapp, the seventh goalie to dress for the Sabres this season, had been called up from Rochester on Friday.
''Definitely not the way you want to play your first NHL minutes (to) see Hack go down like that,'' Knapp said. ''That's probably the majority of how injuries happen (to goalies). We're so focused on the puck.
''It's not a great defensive posture to be down on your knees.''