BOSTON -- It took Nathan Horton six years to make the playoffs.

Once he got there, he showed the value of patience.

Horton scored his second overtime goal of the postseason on Wednesday night, waiting until 5:43 of the extra period in Game 7 to give Boston a 4-3 victory over the Montreal Canadiens and help the Bruins advance to the Eastern Conference semifinals.

"Just getting to the playoffs is all I was really thinking about. This has been a dream come true," said Horton, who never reached the postseason while spending the first six years of his career with Florida Panthers. "I'm really enjoying it. I'm enjoying it more every day."

Boston will open conference semifinals in Philadelphia on Saturday with a chance to avenge last year's epic collapse against the Flyers. The Bruins led that series 3-0 before Philadelphia came back to force a decisive game; in Game 7 in Boston, the Bruins led 3-0 before losing 4-3.

"I get at least until midnight before I've got to start thinking about that," said Bruins goalie Tim Thomas, who stopped 34 shots.

Horton scored on his only shot of the night off a pass from Milan Lucic, setting off a celebration on the Bruins bench and in the stands. It was Boston's third overtime win in the series, including Game 5 on Saturday night when Horton scored 9:03 into the second extra period.

"He's been saving it for seven years, right?" Bruins coach Claude Julien said with a smile. "So he had a lot of game-winning goals in him."

A year after reaching the conference finals, the Canadiens were eliminated by the Bruins for the second time in three years.

"We're disappointed with the end result but you have to give credit to the Bruins," Canadiens coach Jacques Martin said. "Yes, we did have some injuries. We missed some soldiers, but the ones that were dressed gave a really good effort."

Carey Price made 30 saves, and Yannick Weber, Tomas Plekanec and P.K. Subban scored for the Canadiens. Montreal erased deficits of 2-0 and 3-2 but never led in the game.

Montreal won the last of its NHL record 23 Stanley Cup championships in 1993 -- the longest title drought in the history of hockey's most-decorated franchise.

"It's a tough trophy to win," Subban said. "I mean, you never know when it's your year. But this year is not going to be ours."

Johnny Boychuk and Mark Recchi scored in the first 5:33 to give the Bruins a 2-0 lead. But Weber made it 2-1 with a power-play goal in the first and Plekanec tied it in the second with an unassisted, short-handed goal.

After Chris Kelly scored with just under 10 minutes left to give Boston a 3-2 lead, Subban tied it in the final two minutes -- again on the power play.

The Bruins were 0 for 21 on the power play in the series.

But it doesn't matter.

The Canadiens won the first two games in Boston to swipe the home-ice advantage and put the Bruins into a hole they had never been able to recover from before. Boston was 0-26 in series after falling behind 0-2.

But the Bruins came back to win three straight -- including the first two in Montreal, and then Game 5 at home. The Habs won Game 6 on Tuesday night to force a seventh game in Boston.

The Bruins wasted another early lead on Wednesday, jumping out on a slap shot by Boychuk and a wrister by Recchi from the slot that beat Price on the stick side.

Martin took his timeout, and the Canadiens seemed to regroup.

After Michael Ryder was sent off for hooking, Weber scored a power-play goal by converting a cross-ice pass from Michael Cammalleri midway through the first.

Five minutes into the second, with the Canadiens down a man, Plekanec stole the puck from Recchi and broke in alone to wrist it past Thomas and tie it 2-2. But Kelly slid a rebound back under Price with 9:44 left in the third to put Boston back on top.

Montreal tied it after Patrice Bergeron was sent off for whacking James Wisniewski in the face with 2:37 left. The Canadiens set up the power play in the Boston zone and worked the puck around to Subban, who slapped it over Thomas' glove.