The defenseman was injured during the third period of a 3-2 win against the Arizona Coyotes on Thursday.
"Boro's not good to go," Ottawa coach D.J. Smith said after practice Friday. "He has a lot of swelling, and we'll have more of an update this week. I don't know if it's high or low or whatever it is, but it's pretty swollen, so he's not going to play for the next little bit here."
Borowiecki has 18 points (seven goals, 11 assists) in 53 games this season and is tied for third in the NHL with 199 hits.
"His mental preparation, how hard he plays, his leadership in the room," Smith said of what the Senators will be lacking without Borowiecki. "The whole thing will certainly be missed, but we have other guys that will pick up the slack."
The Senators (19-27-11) host the Toronto Maple Leafs on Saturday (7 p.m. ET; CBC, SNO, SNW, SNP, NHL.TV).
"He plays by example," Ottawa forward Nicholas Paul said. "Not only is he a leader off the ice, but on the ice he's the first one to block shots, throw hits, get in there, stick up for our teammates. Having him out of the lineup, it's tough."
