BOSTON — Clarke MacArthur scored the winner 6:30 into overtime as the Ottawa Senators beat the Boston Bruins 3-2 on Sunday afternoon to win their Eastern Conference quarter-final series in six games.

The goal was preceded by Boston right-winger David Pastrnak's holding penalty as he took down MacArthur, who scored on the rebound of Bobby Ryan's shot 36 seconds into the power play.

"You get opportunities like that to put them away, you've got to put them away," said MacArthur, who missed most of the regular season after suffering a concussion in training camp. "It's just awesome that we were able to."

Ryan and Kyle Turris also scored for the Senators and Craig Anderson made 28 saves.

Drew Stafford and Patrice Bergeron scored for Boston. Tuukka Rask had 26 stops.

It was the fourth overtime game of the series. Boston forced a Game 6 with a 3-2 double-overtime win Friday night in Ottawa.

"Game 5 was a long one for us," Anderson said. "Everybody got home late. Guys are working hard and it's a huge letdown after that game for us. We were able to find a way to come out here and make it go to overtime again."

"Obviously the biggest thing is not having to go seven (games) with them," MacArthur added. "They're a resilient group and the injuries they had, they gave us pretty much everything they had. Obviously it's great to end it here. I've had some nightmares in here, and it's nice to be on the other side of it."

Ottawa will face the New York Rangers in the conference semi-finals. New York beat Montreal 3-1 on Saturday to win its quarter-final series in six games.

Ottawa didn't register its first shot until Dion Phaneuf's snapper with 12:18 to play in the first period and came up empty on three power-play chances after a trio of delay-of-game penalties on Boston.

Stafford scored Boston's first opening-period goal of the series at 18:13 on his wrister from the right circle. It was Stafford's second of the series, and it came on a power play after a tripping penalty on Mike Stone.

The Sens tied it with their own power-play goal as Ryan tipped a Derick Brassard rocket past Rask 3:26 into the second. The goal was Ryan's team-leading fourth of the playoffs.

Turris silenced the sellout crowd of 17,565 at TD Garden as he beat Rask high stick side from the slot at 8:32 of the second to put Ottawa ahead 2-1.

Bergeron brought the hometown fans back to life and pulled the Bruins even 1:57 into the third, tucking in a loose puck after Brad Marchand's shot bounced off Anderson. It was Bergeron's first goal of the playoffs.

Ottawa took back the momentum by killing off a Mike Hoffman slashing penalty with 6:26 left in the third to preserve the tie.

Boston was without centre David Krejci, who left Friday's Game 5 after taking a knee-to-knee hit from Senators defenceman Chris Wideman late in the first period. Krejci also missed Games 1 and 2 with an upper-body injury.

Notes: Wideman was scratched after struggling in the Game 5 loss. D Fredrik Claesson was added to the lineup. "I think giving (Wideman) a little break will help him," Sens coach Guy Boucher said. ... Ottawa LW Viktor Stalberg (undisclosed) played despite being a game-time decision. D Mark Borowiecki (leg) and LW Tom Pyatt (upper body) remained out. C Tommy Wingels, a healthy scratch since Game 1, returned to the lineup. ... Boston D Torey Krug (lower body) has resumed skating but did not play.