"He's a very talented player and he gets in front of the net. It's paying off for him right now," Bruins forward Brad Marchand said.
When the Bruins traded Tyler Seguin in the offseason, they received Loui Eriksson, Smith, and two other prospects. Eriksson was the marquee player in the deal, but Smith has yielded the real return thus far. Eriksson has missed time because of two concussions.
"I don't think he was looked upon as a throw-in," Bruins coach Claude Julien said. "It is the first time he has been given the opportunity to play on a regular basis, and he is finally showcasing his skills. It's no fluke."
Smith scored twice in the third period, giving him a team-leading 14 goals. He has five goals and two assists in the last three games.
"He's really taken that opportunity that he's been given, and is on a streak right now," Rask said. "When you're hot, you're hot, just keep shooting."
Eriksson's injuries opened the door for Smith to move from the third line to the second line, alongside Patrice Bergeron and Marchand, and find his groove. Smith also has 16 assists and is second on the team in points.
The Bruins are 13-0-2 in their last 15 home games and have won eight straight in Boston. They haven't lost there in regulation since Oct. 26.
Rask (20-8-2) has allowed one goal or fewer in 15 of his 30 starts this season. After earning only 19 wins last season, he is now the third goalie with 20 NHL wins this season.
Boston tied a club record, set in 1929, by having a player score two goals for the seventh straight game. Smith has done it three times.
Robin Lehner made 36 saves for Ottawa, which has dropped four of five.
"We were really bad. End of story," Lehner said. "Twenty good minutes and 40 bad ones. Teams are picking us apart when we aren't working hard and when we aren't playing hard."
Jarome Iginla beat Lehner with 3:31 remaining in the second when he slammed in a rebound of Torey Krug's slap shot during a power play to make it 1-0.
Ottawa dominated the first period, holding a 15-5 shot advantage, but Boston turned the tables in the second with a 20-8 edge. In addition to the 19 saves in the second period, Lehner was stung by Johnny Boychuk's slap shot, but stayed in the game.
"We hung Robin out to dry," Senators captain Jason Spezza said. "One step forward and one step back. We need to start playing better hockey or they aren't going to let us play much longer."
David Krejci put Boston ahead 2-0 with a shot from the right circle 38 seconds into the third period.
"In the third, getting that early goal by Krejci was a big momentum shift," Iginla said.
Marchand capped the scoring with a short-handed goal with 27 seconds remaining.
The teams will complete the home-and-home series on Saturday at Ottawa.
Bruins LW Daniel Paille returned after missing seven games because of a concussion. ... Ottawa is one of three teams that has never swept Boston in a season series. ... Boston D Dennis Seidenberg sustained a lower-body injury. He won't play on Saturday. ... Bergeron added two assists for Boston, which has outscored its last three opponents 15-3.
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BOSTON, MA - DECEMBER 27: Niklas Svedberg #71 of the Boston Bruins during warm ups prior to the game against the...