PHILADELPHIA — Rookie David Pastrnak scored his first two career NHL goals to lead the Boston Bruins to a 3-1 victory over the Philadelphia Flyers on Saturday.

Chris Kelly added a short-handed goal for Boston, which won its third straight.

Claude Giroux scored for Philadelphia, which fell further out of the Eastern Conference playoff race. Jakub Voracek, who entered leading the NHL with 49 points, assisted Giroux's goal.

The Flyers lost goaltender to injury as Steve Mason left 7:07 into the opening period with a lower body injury. Mason went down and appeared to clutch the back of his right knee after extending his right leg to save Craig Cunningham's shot.

Mason, who was replaced by Ray Emery, has been battling an injury all week. He had an MRI on Monday and was questionable with a lower body injury for Tuesday's game against Ottawa but played in Tuesday's 2-1 shootout victory and again was in net in Thursday's 3-2 overtime victory over Washington.

Boston quickly took advantage of Mason's absence when Pastrnak scored his first career goal with 8:37 left in the first period. Zdeno Chara passed from behind the net to Torey Krug. Krug's shot from the left circle bounced off Emery to Pastrnak, who flipped it past Emery.

It was the first career goal for the 18-year-old rookie, who was playing in his seventh game and second since being recalled from AHL Providence on Tuesday.

The tally ended a six-game road drought on the power play for the Bruins, who had been 0 for 14 on the man advantage in their previous six road games while extending Philadelphia's struggles on the penalty kill. The Flyers entered the day last in the league by killing off 74.8 percent of opponents' power plays.

Boston went up 3-0 with two goals in the third period.

Pastrnak netted his second of the game 4:58 into the period. Pastrnak skated across the blue line, passed to David Krejci and then found an opening to the right of Emery. Krejci whipped a cross-ice pass to a wide-open Krejci, who one-timed it into the empty net as Emery was slow to move laterally. It was the third career point for Pastrnak, who had an assist on Dec. 1 at Anaheim.

Kelly took Loui Eriksson's pass and beat Emery with a wrist shot on the glove side on a 2-on-1 short-handed break with 10:09 left.

Giroux fired a wrist shot from the top of the left circle past Tuukka Rask's stick side with 5:47 remaining.

Notes: Six-year-old Flyers fan Kohlsen Fisher was scheduled to meet Giroux after the game. A video of Fisher's negative reaction to receiving a Penguins jersey as a Christmas gift went viral. . Eriksson returned to the lineup after missing Thursday's win over New Jersey with an upper body injury. . Flyers D Nicklas Grossman (upper body) missed the first game of what is likely to be a three-week absence after getting hurt on Thursday.