In this round last year against Philadelphia, the Bruins became just the third NHL team to lose a series after winning the first three games. Boston even held a 3-0 lead at home in Game 7 before the Flyers rallied again for a 4-3 victory.
Kris Versteeg lifted Philadelphia into a 1-1 tie on Friday at 13:22 of the second period after Lucic scored at 12:02 of the first. Boychuk put Boston ahead at 2:42 of the third, Lucic connected again at 15:03, and Brad Marchand and Daniel Paille added empty-net goals.
The Bruins are in the conference finals for the first time since 1992 and will have home-ice advantage against the Tampa Bay Lightning. Philadelphia was swept 4-0 for the first time since losing to Detroit in the 1997 Stanley Cup finals.
Boston has won seven of eight games and is aiming for its first Stanley Cup title since 1972. Tampa Bay won it all in 2004.
The Bruins began rolling after losing the first two games of their first-round series at home to Montreal. They won the next three games, lost Game 6, and advanced with an overtime win in Boston in Game 7.
Their offense took off against the Flyers. The Bruins won the opener 7-3, then took the second game 3-2 in overtime before returning home for a 5-1 win on Wednesday night.
Now, with Vezina Trophy finalist Tim Thomas performing brilliantly, they've reached the round that eluded them last year. But nine of the 20 players who suited up on Friday night, including Thomas, didn't play in the four losses to Philadelphia a year ago.
Boychuk's game-winner was his second goal of the playoffs. The defenseman got the puck after a faceoff in the left circle. He quickly fired a hard shot to the near side that goalie Sergei Bobrovsky couldn't grab with his glove.
Bobrovsky, who started Game 1 of the series, got the start again with the season on the line. He replaced Brian Boucher, who had been ineffective in the other losses.
The Bruins had taken their 1-0 lead on a power-play goal by Lucic, who led them with 30 goals in the regular season. David Krejci sent a pass from the left circle to Nathan Horton at the left corner of the crease. Horton quickly fed Lucic on the other edge of the crease for an easy goal, his first of the playoffs, into the open side of the net.
It was Boston's second goal in three power plays after going scoreless on its first 31 in the postseason.
The Flyers tied it when Versteeg went in alone and beat Thomas after Mike Richards stole a pass by Marchand.
Boston had been the aggressor with an 18-9 advantage in shots midway through the second period. But Versteeg's goal seemed to energize Philadelphia, although the Flyers had a tough time capitalizing after committing two penalties in the last 3:05 of the period.
The Bruins were putting pressure on the Flyers when Marchand tried to pass across the ice from near the right point. Instead, he put the puck right on Richards' stick. Richards skated slightly ahead of Boston defenseman Dennis Seidenberg before giving the puck to Versteeg, who scored his first of the playoffs.
Notes: Philadelphia was without D Chris Pronger for the third straight game with a hand injury. ... Boston D Adam McQuaid missed his second consecutive game with a sprained neck after crashing into the boards headfirst in Game 2. ... The Flyers lost last year's Stanley Cup finals in six games to the Chicago Blackhawks.
