The Bruins are leading the division by three points over Ottawa, but Boston has lost three of its last four games and has posted a 4-6-1 record in February.
Meanwhile, the Senators enter tonight riding a four-game winning streak and a 5-0-1 mark in their last six games. However, the club will be forced to play without No. 1 goaltender Craig Anderson, who is sidelined after suffering a freak injury.
Anderson was in net for all four games during Ottawa's current win streak, but he suffered a lacerated right pinky finger while preparing a meal on Wednesday and is out indefinitely. Anderson, who is 29-19-6 this year, will be replaced as the team's primary starter by Alex Auld and Robin Lehner has also been recalled from Binghamton of the AHL.
Thanks to Anderson's solid play all season long, Auld has been used sparingly this year, going 2-3-2 in 13 games (7 starts). The veteran backup is confident he can get the job done while Anderson is on the shelf.
"It's my role. That's why I'm here," Auld said after practice on Friday. "I'm looking forward to it and I look at it as an opportunity. Craig is a huge part of our team and it's a tough loss, but I think we have a capable group and we're playing good hockey. We've just got to keep that going."
In addition to playing without their top goaltender tonight, the Sens will also face a Boston team that has won seven straight in this series overall. The Bruins have also taken seven in a row and 10 of the last 11 meetings at Scotiabank Place.
Anderson's last start before the injury came in Tuesday's 5-2 win over visiting Washington. He stopped 33-of-35 shots and Milan Michalek tallied twice to lead Ottawa to the easy victory.
Karlsson has set a franchise record for points in consecutive games by a defenseman with three goals and four assists over his last two outings. With 60 points on the year, the 21-year-old Karlsson is just three shy of tying Norm Maciver's club record for points in a season by a defenseman. Maciver had 63 points for Ottawa during the 1992-93 season.
Ottawa is 16-11-3 as the host this season. After completing a three-game homestand tomorrow against the New York Islanders, the Senators will visit Boston for a rematch on Tuesday.
Boston posted a 4-2 win Wednesday in St. Louis, but the Bruins dropped a shootout decision last night in Buffalo. The setback dropped the Bruins to 2-2-1 on six-game road trip that ends tonight.
Derek Roy scored in the fourth round of the shootout to lift the Sabres to the 2-1 win. Roy faked to the backhand before lifting a shot off the right post and past Tuukka Rask. Benoit Pouliot had the final chance for Boston, but Ryan Miller made the glove save on the wrist shot for the win.
"It was a close game and they played really well," said Chara. "The goalies on both sides made some huge stops. It's just a shame that we didn't get the extra point."
Boston has not had consecutive wins since January 10 and 12, going 8-9-2 during that time.
The Bruins have almost identical records at home and on the road this season. Boston is 18-10-1 as the guest and 18-10-2 at TD Garden.