BOSTON - It almost looked like a replay. Noel Acciari posted up in the slot, tipping a point shot past Craig Anderson to get the Bruins on the board in the second period.
In Game 3, the bulky winger, playing in his first career postseason game, set in motion the Black & Gold's comeback with a tip of a John-Michael Liles wrister. He followed nearly the exact same script in Game 4, this time deflecting a Charlie McAvoy shot from the right point past Craig Anderson for what appeared to be a 1-0 lead.
The difference on Wednesday night was the sliver of white in between Acciari's skate and the Senators blue line.
Ottawa believed the play was offsides and asked for the play to be reviewed. After further examination by the officials, it was determined that nearly some 20 seconds prior to the goal, Acciari entered the zone ahead of the puck, nullifying his second tally of the series and leaving the Bruins still in search of their first goal.
Boston never found it. Despite a number of close calls, the Bruins failed to solve Anderson and dropped a 1-0 decision to the Senators in Game 4. They now trail the series, 3-1.
"I mean I was excited, it was an exciting time of the game. I just scored the first one of the game and got the team going," said Acciari. "I was definitely excited, but things happen and I was offsides, so nothing I could do."
In a series that has seen all four games decided by one goal, having one wiped off the board was a crushing blow.
"The offsides challenge - that really has no bearing on the play - calls that back," said David Backes. "I think that for some reason made us pause rather than realize that we broke the mold there and had the recipe for success and to keep doing that.
"I think it's another one-goal game, another tight-checking game and they're able to push through and get that one play and we don't."
Video: R1, Gm4: Senators @ Bruins
Following the negated Acciari tally, the game remained scoreless until the 5:49 mark of the third period. That's when Erik Karlsson and Bobby Ryan - two players who have given the Bruins fits in this series - hooked up for the game's lone goal.
Karlsson corralled the puck at the point and sent a slap pass to Ryan at the left post. A sprawling Tuukka Rask (26 saves) stopped Ryan's first attempt, but his second try squeaked over the goal line to give Ottawa a 1-0 lead they would not relinquish.
"I think it hit somebody's skate. I didn't see [Karlsson] releasing that puck, but I think it hit a skate and just [went] to the back door," said Rask. "I had my stick on it, and I just couldn't pull it back, and then [Ryan] had an extra second and just stuffed it in."
Ryan (three goals, two assists) and Karlsson (five assists) are pacing the Senators with five points apiece in the series.
"A night like tonight, I thought we defended fairly well," said Bruins interim head coach Bruce Cassidy. "Karlsson, he popped out of nowhere. We know that. We've identified that he's their best player, but that doesn't mean he's not going to get his opportunities...their goal, obviously, we weren't good enough in D-zone. We had a missed assignment and they out willed us at the night.
"You've got to give him credit. He's a good player, Bobby Ryan. We've seen that in this series. He's a big body and that ends up being the difference in the game."
The Bruins, meanwhile, managed just five shots in the third period. But while the opportunities were limited, they felt the chances they did get were good ones.
"I thought we did a pretty good job down there," Brad Marchand said of the team's play in front of Ottawa's net. "We had a lot of really good opportunities and their goalie made some big saves, so you've got to give him credit. He's a good goalie."
Video: BOS@OTT, Gm4: Cassidy on loss to Sens in Game 4
Boston knows it has to find ways to break through offensively in Game 5 if it wants the series to return to Causeway Street.
"Just bring some more pucks on net and more rebounds I think," said Patrice Bergeron. "We're having some good looks but too many of them are just one and done and we have to make it a little harder for [Anderson] to see the puck."
It's must-win time for the Black & Gold. They have never won a series when trailing three games to one.
"We have to face reality here and come out with our backs to the wall in their building - these things are taken one game at a time," said Backes. "Take care of business in their barn and get it back here and change momentum of the series, that's our focus now.
"We've got to stick together, build this together and keep playing together and get that result that we're looking for. We're playing pretty good, we've had that rhetoric before but this is playoff time, this is result time and we need the results. We haven't got in in the last three games and we need to get back to it."