At 5:49 of the third period, Sabres forward John Scott was given a match penalty for illegal check to the head on Eriksson. The Bruins forward left the game and did not return.
Scott also received a fighting major for his battle with Boston defenseman Adam McQuaid.
"The referees called it the way I guess everybody saw it," Bruins coach Claude Julien said. "It's unfortunate but the guy who did it did his job tonight. He's out there for two reasons and that's either to fight or to hurt. He did his job tonight."
Bruins general manager Peter Chiarelli said in a statement that Eriksson would stay overnight in Buffalo for precautionary reasons but is expected to return to Boston on Thursday.
Sabres coach Ron Rolston said he did not want to comment on the hit; Scott was not made available to the media after the game. The Buffalo forward was offered the opportunity for an in-person hearing with the Department of Player Safety for the hit.
Krug, a defenseman playing in his first full season with the Bruins, scored his second goal of the period on the ensuing power play to make it 5-2.
"We needed to score on that and we did," Julien said. "That was a big goal for us. We kept playing our game right to the end. We've got some important things here going on, so we have to focus on that and we had to finish the job here tonight."
"For us to get one on the power play was good not only for this game but for the next one and maybe get a bit of confidence going into the next one," Krug said. "It's all about results right now."
Lucic started the scoring at 10:01 of the first period with his fourth goal of the season, deflecting a Jarome Iginla shot past Ryan Miller.
Lucic took a puck in the face late in the first period after Sabres defenseman Mark Pysyk's pass went awry. His injury brought cheers from some of the 17,645 fans at First Niagara Center. He returned after taking five stitches and added his second goal of the night 40 seconds into the second period to make it 2-0.
"Obviously when you get hit in the face like that it's never a good feeling, so it was good to come out and have a good first shift in the second period," said Lucic, who assisted on Krug's second goal for a three-point night. "Actually, I almost hurt myself even more when I crashed in the boards after that, but it was nice to get one also when the crowd is cheering when you get in the face. It was nice to stick it to them that way."
The Bruins took a bench minor for too many men at 7:38 of the second period and the Sabres capitalized when Cody Hodgson tipped in Thomas Vanek's pass to make it 2-1 at 8:21.
The Bruins made it a two-goal game again at 11:50 when Dougie Hamilton scored his second goal of the season, converting Brad Marchand's cross-crease pass. The Sabres cut into the lead again when Nikita Zadorov scored his first NHL goal at 15:10.
"I'm really happy right now," Zadorov said about his goal. "It's really hard to play against these guys."
Krug put the game away with two third-period goals.
"It was nice to have some situations. There wasn't a lot of shots," Johnson said. "There was a couple of good chances there but it was nice to get the two points."
Miller stopped 29 shots for the Sabres (1-9-1), who go on the road to face the Florida Panthers on Friday.
"I think we could've done a little more to stay in that third period," Miller said. "I need to come up with some saves for the guys. Two goals aren't very good. That's about the most disappointed I've been with myself all year. So 3-2 at home, you got to give guys an opportunity, just two goals go through me. That's not going to get it done."