ST. LOUIS -- The Boston Bruins expected the Stanley Cup Final against the St. Louis Blues to be a battle.
It definitely is one after the Blues won 4-2 in Game 4 at Enterprise Center on Monday.
With the best-of-7 series tied heading back to Boston for Game 5 on Thursday (8 p.m. ET; NBC, CBC, SN, TVAS), the Bruins are the team that needs to respond after the Blues answered a 7-2 loss in Game 3 on Saturday with a relentless, physical effort.
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"I don't think it's a surprise to anybody," Boston goalie Tuukka Rask said. "We've just got to go home and take care of business and do our best. It's a best out of three now. So I think that's what everybody expected."
But it wasn't what the Bruins wanted, especially when they had a chance to take a 3-1 series lead and looked like the superior team in Game 3. Their challenge might be even tougher if defenseman Zdeno Chara is unavailable for Game 5.
The captain left at 3:07 of the second period and didn't return after being struck in the mouth with deflected puck. Bruins coach Bruce Cassidy did not know Chara's availability for Game 5 but can see the impact the war of attrition in the Stanley Cup Playoffs is having on his defensemen.
Boston was already missing defensemen Matt Grzelcyk and Kevan Miller. Miller hasn't played in the postseason because of a lower-body injury and is not expected to play in the Cup Final.
Video: Zdeno Chara's status is currently unknown
Grzelcyk sat out his second straight game and is in the NHL concussion protocol after being injured on a hit by Blues forward Oskar Sundqvist in Game 2. Sundqvist received a boarding penalty and was suspended for Game 3 by the NHL Department of Player Safety but returned for Game 4. The Bruins don't know when Grzelcyk will be ready to play.
"We're not sure on [Chara] going forward or [Grzelcyk] for that matter," Cassidy said. "They both may be available for Game 5 or neither. So we've got to make the adjustments."
The positive for the Bruins is they hung with the Blues and the score was tied 2-2 midway through the third period even though Boston had to play most of the night with five defensemen for the second time in the series. But the Bruins made sloppy mistakes that proved costly, including one on Ryan O'Reilly's go-ahead goal at 10:38 of the third.
A slow line change allowed defenseman Alex Pietrangelo to step into a slap shot from the top of the right circle and O'Reilly to sneak between Bruins forward Danton Heinen and defenseman Charlie McAvoy to put the rebound in for his second goal of the game.
"The mistakes matter," said Boston defenseman Brandon Carlo, whose shorthanded goal tied it 2-2 with 5:41 remaining in the second. "Everything matters at this point in the year. That's that difference between going (up) 3-1 in the series and (being) tied 2-2. Everything is definitely huge."
The Bruins expected the Blues to have a strong pushback after losing 7-2 in Game 3 but were caught on their heels from the start. O'Reilly's wraparound goal at 43 seconds of the first period gave St. Louis the early lead it wanted and led to Boston chasing for most of the night.
Charlie Coyle's goal on a rebound at 13:14 of the first period made it 1-1, but Vladimir Tarasenko scored on a rebound 2:16 later to put the Blues back ahead 2-1 at 15:30.
Video: Melrose and Hradek wrap up Game 4 from St. Louis
"They were winning loose pucks, winning their battles," Coyle said. "They came hungry, and we need to do a better job. When we have those good starts, we do the right things, we outwork them, and we support each other well, that's when we give ourselves a great shot and we seem to kind of snowball after that. We didn't have it as much as they did tonight."
The Blues set the tone with a physical first period when they outhit the Bruins 24-16. Their fourth line of Ivan Barbashev (five), Sundqvist (three) and Alexander Steen (four) combined for 12 hits in the first period.
St. Louis outhit Boston 44-41 for the game. Barbashev had a game-high nine hits.
"I think we are wearing them down when they don't have six D-men," said Sundqvist, who had four hits. "Obviously you don't want to see a guy take puck in the mouth. … But, five D against our forecheck, I don't think it's that easy."
Cassidy acknowledged the physical strain on his defensemen while also calling out the Bruins forwards for not doing more to help them. The second line of Jake DeBrusk (two shots, four attempts), David Krejci (no attempts) and David Backes (one shot, one attempt) combined for three shots on goal Monday, and DeBrusk's two power-play assists are their only points in the series.
Boston's first line of Brad Marchand, Patrice Bergeron and David Pastrnak has yet to score a point at 5-on-5 in the series, though Marchand and Bergeron assisted on Carlo's shorthanded goal.
"Personally, I think our forwards have to do a way better job with our D out," Cassidy said. "The onus has to go on them. They have to pull their weight in terms of puck supported and helping out the D, finishing some plays. We had some lines tonight with very few shot attempts. To rely on a 2-1 game, we can win those games, but they're going to have to pull their weight, especially if these guys are out.
"That's just the way it is. That's the hand we're dealt."
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