A last-minute addition to Boston's lineup, Matt Fraser went from no goals this season to two on consecutive shifts in the second period.

Fraser scored twice in a span of 1 minute, 28 seconds, and the Bruins held on for a 4-2 win over the Ottawa Senators on Saturday night.

"You try and prepare the same way as if you were playing every night, but when it comes down to it, mentally it's almost easier when they tell you just after warmups that you're going," said Fraser, a healthy scratch in Boston's previous five games.

Fraser, who didn't know he was playing until center David Krejci was scratched with an undisclosed injury, came through with the first multipoint game of his career.

Fraser broke a 1-all tie on a one-timer off a rebound with 8:46 left in the second, then scored again on his next shift. His second came on a high wrist shot over Ottawa goalie Robin Lehner's glove.

"I don't know if the net looked that big or if my eyes just looked that big," Fraser said. "I was glad that both pucks went in."

Carl Soderberg assisted on both of Fraser's goals and Tuukka Rask made 28 saves for the Bruins, who have won three of four. They had one of their most solid games since defenseman Zdeno Chara injured his left knee Oct. 23.

Rask said the Bruins just passed the puck better than they had been.

"That hasn't been our strength in the past games. It's kind of been up and down," Rask said. "We need crisp passes and tape-to-tape passes because that helps us to break out and gives us the edge. Today was a good example of that."

Brad Marchand and Dennis Seidenberg also scored for Boston, which held Ottawa to five shots in the first period. The Senators felt fortunate that one got past Rask when Mark Stone scored on a breakaway with 28 seconds left in the first period.

"There were stretches of the game where I thought we played well, but we never established much of a forecheck all night. They were getting out of their zone quite easily," Stone said.

Mika Zibanejad added a goal for the Senators in the third, and Lehner finished with 25 saves.

The Senators never recovered after Fraser's goals in the second quickly turned a 1-all tie into a 3-1 lead for Boston. Fraser had three career goals entering the game.

"He certainly didn't miss his opportunity tonight," Boston coach Claude Julien said.

Marchand scored the game's first goal with 1:06 left in the first. Patrice Bergeron assisted, winning a faceoff and slipping the puck behind him to Marchand for a shot that got through Lehner's pads and trickled over the goal line.

The Senators answered with a late goal of their own when Stone stole the puck from Seidenberg and beat Rask on a breakaway to tie it.

"Tough break on that goal there, but we didn't let that deflate us. We battled back and played a pretty solid second and third," Rask said.

Seidenberg scored 2:08 into the third to give Boston a 4-1 lead.

NOTES: The Bruins held a moment of silence for former Boston Mayor Tom Menino, who died Thursday. That was followed by a brief slide show that concluded with a photo of Menino at his desk with the Stanley Cup. ... After being outshot 10-5 in the first period, Ottawa outshot Boston 10-9 in the second. ... Ottawa D Eric Gryba played in his 100th career game just down the road from where he played in college at Boston University. ... It was the third straight game in which a Boston player scored twice.