The Bruins are in familiar territory: with their backs against the wall.

Their battle through adversity has been well documented over the past few months. Tonight, they face their biggest obstacle of the season – an elimination game.

Win and you extend the series at least for one more game in Boston on Sunday afternoon. Lose and the season is over.

The task is a tall one, indeed. And even taller without Brandon Carlo, Torey Krug and Adam McQuaid – three of their top-four blueliners.

Against a team that has had their number this year, and against a couple of players that they have yet to find an answer for in Erik Karlsson and Bobby Ryan, the Bruins are going to need to find answers quickly against their Atlantic Division rivals. Otherwise, they’ll be cleaning out their lockers and reserving their tee times on the golf course in a matter of days.

Gametime: 7:30 pm
TV/Radio: NESN, USA/98.5 The Sports Hub
Series: Senators lead, 3-1
Location: Canadian Tire Centre

Bruins projected lines

Brad Marchand-Patrice Bergeron-David Backes
Drew Stafford-David Krejci-David Pastrnak
Riley Nash-Dominic Moore-Noel Acciari
Tim Schaller-Sean Kuraly-Frank Vatrano

Zdeno Chara-Charlie McAvoy
John-Michael Liles-Colin Miller
Joe Morrow-Kevan Miller

Tuukka Rask
Anton Khudobin

Senators projected lines

Ryan Dzingel-Kyle Turris-Alex Burrows
Viktor Stalberg-Derick Brassard-Bobby Ryan
Mike Hoffman-Zack Smith-Mark Stone
Clarke MacArthur-Jean-Gabriel Pageau-Chris Kelly

Marc Methot-Erik Karlsson
Dion Phaneuf-Cody Ceci
Ben Harpur-Chris Wideman

Craig Anderson
Mike Condon

Tonight’s storylines

– Maybe it’s not a surprise just based on his performance, but the news of Ryan Spooner being left out during line rushes might have caught some fans a little off-guard. At the same time, there’s some justification for sitting the enigmatic Spooner, who has a pair of assists and only two shots on net in the first four games of the series. Sean Kuraly took Spooner’s spot with Tim Schaller and Frank Vatrano – who appears ready to go after leaving Game 4 with a walking boot – on the makeshift fourth line.

– Meeting the media Friday morning, interim head coach Bruce Cassidy admitted that Spooner is not 100 percent and thinks Kuraly is a better choice right now. In just two postseason games, Kuraly has one more shot on goal than Spooner, though one has to wonder why Matt Beleskey wasn’t considered to be reinserted into the lineup as well. Even with his struggles through injuries and inconsistencies in 2016-17, Beleskey was a noted playoff performer with the Ducks, and at the very least could have given the Bruins a little more postseason experience in a must-win Game 5. And even if the Bruins force a Game 6, one has to wonder if this is the last time that Spooner, who is an RFA at the end of the year, dons the ‘Spoked B.’

– In desperate need of a spark, the Bruins are hoping to get all four lines to contribute in Game 5. More importantly, they need their best players to come through in desperate times. Brad Marchand and David Pastrnak have both shown spurts of good play, but neither has been consistent in their attempts to get behind the Sens 1-3-1 trap and capitalize on scoring chances. With frustrations settling in throughout the lineup, the Bruins need their leaders and top performers to stand up, and it starts with the likes of Marchand, Pastrnak, Patrice Bergeron, David Krejci, Zdeno Chara and David Backes, just to name a few.