Jim Montgomery, who went 180-84-33 in two-plus season as the Bruins coach was fired on Tuesday. Spenser Heaps/Associated Press

BOSTON — Boston coach Jim Montgomery, who led the Bruins to the greatest regular season in NHL history but never got them past the second round of the playoffs, was fired Tuesday, a day after the below-.500 team lost to last-place Columbus to extend its losing streak to three games.

Assistant Joe Sacco, who led the Colorado Avalanche to a 130-134-40 record from 2009-2014 and was a finalist for coach of the year in his first season, will lead the Bruins on an interim basis.

Montgomery, 55, was fired 20 games into his third season in Boston and a day after a 5-1 loss to Columbus in which the Bruins allowed two short-handed goals. He leaves with a 8-9-3 record this season and a 180-84-33 mark in his career, which also included one-plus season in Dallas.

“Today, I made a very difficult decision with regards to a coaching change. Jim Montgomery is a very good NHL coach and an even better person,” said Sweeney in statement. “He has made a positive impact throughout the Bruins organization, and I am both grateful and appreciative of the opportunity to work with him and learn from him.

A genial hockey lifer who led Maine to the 1993 NCAA title – scoring a third-period hat trick in the final – Montgomery played in 122 NHL games over six years before he turned to coaching. He won two U.S. junior titles and led Denver to an NCAA championship before he was hired by the Dallas Stars.

In his first season on the bench, Dallas made the playoffs for the first time in three years. In his second, the team would reach the Stanley Cup Final but with a new coach.

Montgomery was fired 32 games into the year for what the team called unprofessional conduct. He has since admitted to binge drinking to the point of blackouts and conceded that he deserved to be fired. After going through rehab, he was hired as an assistant in St. Louis and then for the head coaching job with the Bruins.

In Boston, Montgomery replaced Bruce Cassidy – another likeable Bruins coach whose teams racked up 100-point seasons but flamed out in the postseason. Cassidy was fired three years after leading Boston to the 2019 Stanley Cup Final and hired by Vegas eight days after the Bruins fired him.

The Golden Knights won the Stanley Cup in his first season.

The Bruins finished with more than 100 points in each of Montgomery’s first two seasons – including a record-setting debut, when their 65 wins and 135 points were both the most in NHL history. But the team lost in the first round of the playoffs that year and advanced to only the second round last season.

The struggles carried over into the new season, with an opening night loss to Florida in which they fell behind 5-1 and an 8-2 loss to Carolina on Halloween. After the Monday night loss to Columbus in which the team was booed off the ice at home after falling behind 3-0 in the first period, Montgomery grew philosophical.

“Everyone goes through struggles. Whether in life, or your team,” he said. “That’s what life’s about. How do you pick yourself up? It’s not how hard you fall. It’s how quickly you pick yourself up.”

The Bruins’ best hope is that the move kick-starts a roster with high-end talent that hasn’t been performing.

All-Star David Pastrnak has a negative plus-minus, which would be a first in his career, and managed no shots on Monday; Brad Marchand is in the negatives for the first time since he became a full-time NHLer. As a team, the Bruins have given up 21 more goals than they’ve allowed – third-worst in the NHL.

“Definitely not happy with the way that things are going,” Marchand said Monday night. “We need to be much better in a lot of areas. … It’s not acceptable to continue to have the same mistakes and do the same things over and over that aren’t bringing us success. So, yeah, we need to be a lot better.”

But the biggest problem has been the goaltending.

And that can’t be blamed on the coach.

A year after alternating two No. 1 goalies for the entire regular season – and finishing with more than 100 points for the sixth full season in a row – the Bruins came out of training camp with none. General Manager Don Sweeney traded 2023 Vezina Trophy winner Linus Ullmark over the summer – before agreeing to a new contract with former University of Maine star Jeremy Swayman.

The timing emboldened Swayman’s holdout, and the 25-year-old from Alaska didn’t agree to a new deal – eight years and $66 million – until the eve of the regular season. His numbers (5-7 record, .884 save percentage, 3.47 goals-against average) may be the hangover from missing training camp; Jonas Korpisalo (3-2, .901, 2.74), who was acquired from Ottawa over the summer, hasn’t been the answer either. “I think I’ve had enough time now to adapt and get back to things,” Swayman said Monday night. “I’m really trying to to engulf just being in a room again and being a leader and I want my play to speak for that. So I need to step up, and that’s exactly what I’m going to do.”