BOSTON — The Bruins didn't seem like the team with the most to gain until it was too late Sunday night.
Roberto Luongo came off the bench to shut down Boston in the third period, and the Florida Panthers dashed the Bruins' hopes of getting the top seed in the Eastern Conference playoffs with a 4-2 win.
The Bruins trailed Tampa Bay by a point heading into the regular-season finale but couldn't top a Panthers team that was eliminated from postseason contention Saturday.
"You would have hoped the urgency would have been there with an opportunity to win the division," Bruins forward David Backes said. "We had it in the third, but needed it right from the get go."
Boston will host the Toronto Maple Leafs in the first round beginning Thursday night. The Leafs were 3-1 against the Bruins in the regular season.
Florida starter James Reimer left in the third with an injury, and Luongo came in and stopped eight shots over the last 8:07. The pair combined to make 41 saves.
Henrik Borgstrom, Frank Vatrano, Maxim Mamin and Evgenii Dadonov scored for Florida.
Backes and David Pastrnak had a goal each for Boston, with Pastrnak cutting it to 3-2 shortly before Reimer was hurt. Tuukka Rask made 22 saves.
"We didn't deserve to win and that's the reality," Rask said. "I think it's mental, just not being sharp enough at the drop of the puck."
After beating the Bruins for the second time in three games, Florida is headed home despite an impressive 25-8-2 run to end the season, including winning their last five.
"It's disappointing. We were really hoping that we'd get a little help from some other teams and maybe get in," Panthers forward Vincent Trocheck said. "I think there's a lot of teams that didn't want to play us if we did make it in."
Trailing 3-1 heading into the third, Boston made a furious surge, outshooting Florida 26-6 but only scoring once.
Pastrnak scored a power-play goal at 9:54 of the third. Pastrnak led the Bruins with 35 goals and had a career-high 80 points.
"It has been a tough schedule for us but that's not an excuse," Pastrnak said. "The last few weeks have not been our best."
Dadonov put the game away when he scored an insurance goal with 1:49 remaining.
"Would have been easy for them to come and in and shut it down but it's a competitive league," Bruins forward Brad Marchand said.
Boston had been unbeaten in regulation over its last 11 home games and had beaten Florida in 12 of 13 overall.
Boston lost in the first round last year to Ottawa in six games after failing to make the playoffs the two previous seasons.
NOTES: Marchand failed to score in the Bruins' final six games, and David Krejci has one goal in 16 games. ... Borgstrom scored his first career goal. ... Florida D Keith Yandle tied his career high with his 48th assist.