BOSTON - The Boston Bruins lost starting goalie Tuukka Rask 90 minutes before the faceoff, blew their regular-season finale midway through the game and said goodbye to the playoffs before the day was over.

With Rask out sick for the Bruins' last-gasp run at the post-season, backup Jonas Gustavsson allowed four goals in the first half of the second period and the Ottawa Senators went on to win the regular-season finale 6-1.

Boston was eliminated from playoff contention later Saturday when the Philadelphia Flyers beat Pittsburgh 3-1.

"I don't know if we thought it was going to be easy or what," Bruins defenceman Torey Krug said after the game, but before Philadelphia clinched the final post-season berth in the Eastern Conference. "We came out and just failed in the second period."

Chris Neil, Zack Smith, Matt Puempel and Mika Zibanejad scored over 8:18 in the second period, and Andrew Hammond stopped 39 shots for the Senators. Ottawa also had a pair of empty-net goals in the third when the Bruins pulled Gustavsson to create a two-man advantage on the power play.

David Pastrnak scored for Boston, and Gustavsson stopped 30 shots. The loss left Boston tied with Detroit with 93 points but trailing the Red Wings, who lost to the New York Rangers on Saturday, in the tiebreaker.

The Bruins could have still made the playoffs if the Flyers earned no more than one point in their last two games. The victory over Pittsburgh gave Philadelphia 94 points and left Boston in ninth place in the East.

"We could have controlled our own fate," Bruins coach Claude Julien said before Philadelphia's victory. "Right now, all we can do is cross our fingers and hope for a miracle."

The Bruins' chances of avoiding a second consecutive missed post-season were damaged when Rask, the 2014 Vezina Trophy winner, was scratched from the starting lineup with what the team said was an "illness." Rask was with the team for the pregame warmup, but he spent most of it near the bench while Gustavsson took practice shots in the net.

Gustavsson, who hadn't started since March 18, stopped all 17 shots he faced in the first period and was spotted a 1-0 lead when Pastrnak received Brad Marchand's lofted pass over the blue line and beat Hammond just 5 minutes into the game. Pastrnak appeared to be offside, but the referee couldn't find a replay angle that was conclusive.

In the second, the Senators quickly turned things around.

Neil scored 1:42 into the period, swiping twice at a rebound before it skittered under Gustavsson. Four minutes later Smith deflected Erik Karlsson's shot into the net; three minutes after that, Phil Varone slid a backhand into the slot and Puempel tapped it between Gustavsson's legs; at 10 minutes even, Zibanejad deflected another one into the net to make it 4-1.

Fans who had chanted "We want playoffs!" earlier in the game were now booing the hometown team. Julien called a timeout and the Bruins mustered some good chances later in the period but couldn't close the gap.

Senators coach Dave Cameron said he was less interested in playing spoiler than just seeing his team finish the season well.

"It wasn't about Boston today," he said. "We knew what was at stake for Boston and we knew if we had any advantage in the game today, all the pressure was on them."

Twice in the third period, the Senators picked up penalties and Julien pulled the goalie to create a two-man advantage. Both times, Ottawa scored empty-net goals, the first by Jean-Gabriel Pageau and the second by Smith.

Julien was retained last year after general manager Peter Chiarelli was fired and replaced by Don Sweeney. The Bruins have not retained a coach after missing the playoffs two years in a row in 50 years, since Milt Schmidt was given a third season in 1965-66 before giving way to Harry Sinden.

NOTES: With 85 points, the Senators finished 11th in the Eastern Conference and missed the playoffs for the second time in three seasons. ... The Bruins announced team awards before the game: F Matt Beleskey was given the Eddie Shore Award for exceptional hustle and determination; F Loui Eriksson was given the Elizabeth Dufresne Trophy for outstanding performance during home games; F Jimmy Hayes earned the John P. Bucyk Award for his charitable work.