DENVER — Against the Colorado Avalanche Wednesday evening, Zdeno Chara — key to Boston’s strategy of defending the opposing No. 1 line of Gabriel Landeskog, Nathan MacKinnon and Mikko Rantanen — exited the game after nine shifts and 5:24 with an apparent left knee issue. The defenseman’s leg buckled as he hit former teammate Carl Soderberg with 1:07 left in the first period. He finished his shift, appearing to favor his leg for 27 seconds until DeBrusk took a Colorado turnover in for a goal that made it 2-1.
The Bruins called it a lower-body injury. A team spokesman said they would issue an update Thursday on Chara if appropriate. A scheduled practice and media availability in Dallas was canceled.
Coach Bruce Cassidy was unsure whether Chara. who walked out of the Pepsi Center with a slight limp, would be assessed before the Bruins’ date with the Stars on Friday, or be sent back home to Boston.
With Chara out the final 40-plus, the Bruins (10-6-2) saw the tide change against them. It was not a good night for Jaroslav Halak, who was leaky. He saved 19 of 25 shots, his worst performance of the season, unable to lift a battered five-pack of blueliners.
“Your goaltending needs to be a little sharper,’’ Cassidy said. “That’s just a fact. It was great last weekend. Tonight, he wasn’t on top of his game. We didn’t get away with it.’’
The Avalanche (9-6-3) started their comeback at 8:47 of the second. On the penalty kill — an area of Chara’s expertise — Halak couldn’t squeeze Rantanen’s wrister.
Colorado’s Matt Calvert, credited with a goal 2:11 into the third, tied the score at 3-3 when a backchecking defenseman Steven Kampfer kicked the puck past Halak. The goaltender said his stick was kicked away from him — and was frustrated officials didn’t review it — but the play began when Kampfer made an ill-advised, failed pinch at the offensive far blue line, creating a 2-on-1.
“Down guys on the back end, of course that affects our hockey club,’’ Cassidy said. “Some of those mistakes, we could have helped ourselves.’’
Such as when Colorado scored the go-ahead goal with 9:02 left. With Boston’s top line unable to hold the puck in the offensive zone — Brad Marchand was caught up ice after whiffing on a stick check — Rantanen led a 3-on-2 break on Jeremy Lauzon and John Moore. Both defenders sagged back as Rantanen, driving middle, hit MacKinnon on his flank. A snapshot snipe, and Colorado opened the throttle.
With 4:21 remaining and David Krejci (holding) in the box, Tyson Jost tapped another Halak leak across the line. Alex Kerfoot scored a PPG with 14 seconds left.
“I thought our first 40 was sold,’’ Patrice Bergeron said. “A lot of missed opportunities in the first. … It got out of hand. We didn’t play the right way.’’
The Bruins hit three posts in the first period, but held a 2-1 lead after 20.
Colorado captain Gabriel Landeskog — who took a heavy hit from Bergeron early — snuck free from soft coverage and ripped a loaded wrister past Halak at 10:16 of the first. Then the Bruins started the bell-ringing chorus.
First David Pastrnak from the doorstep, after intercepting a Landeskog giveaway. The snakebitten David Backes clanked one on the rush. After Bergeron rang iron on the power play, Boston’s second power-play unit found a 1-1 goal 16:43 in.
The net-front screener on the Bruins’ No. 2 power play unit, Backes parked himself in front of Semyon Varlamov as a Krejci slap-pass arrived from the circle. The entry tipped off the sticks of Backes and Pastrnak, who was double-shifting on the Bruins’ PP2 unit. He was credited with his league-best 17th goal of the year after skating 1:53. It was Backes’ first point of the year.
The Bruins’ second line, victimized on the first goal, got one back in the final minute of the first.
MacKinnon missed connections on a back pass to defenseman Samuel Girard, and DeBrusk went into full flight. Collecting the puck just inside the center-ice circle, he went backhand-forehand and beat Varlamov to make it 2-1 with 40 seconds left.
At 3:05 of the second, DeBrusk made it 3-1 by tipping a Pastrnak point drive on the power play. It was his fourth career two-goal game, his third in the last 33 days.
But Colorado, which was 1-3-1 in November entering the night, started its climb with that PK goal, taking advantage of Chara’s departure.
Now the question is: will other teams do the same?
Call-up Jakub Zboril, a left shot, would make his NHL debut on Friday in Dallas if Chara cannot go. Unless Brandon Carlo (upper body) makes the long flight out, the Bruins could be without four of their top five defensemen: Chara, Charlie McAvoy, Carlo and Kevan Miller, who practiced with the team Wednesday.
Entering the season, the Bruins had too many defensemen. Knowing the nature of hockey injuries, they were careful not to call it a surplus.
“It’s our whole right side, for one thing, you know?’’ Cassidy said of those hors de combat. “And now you’re talking about your top guy on the left side. Your second guy on your left side, [Torey] Krug, is really still finding his game. He missed a lot of time. You’ve pretty much got your whole D-corps out.’’
“We’ve got to be careful in terms of how we talk to that group. By the same token, it’s their opportunity to play,’’ he said. “We don’t make excuses.’’